22102 Basic Science Chemistry Question Bank with Answers & Explanation for Multiple Choice Questions
22102 Basic Science (Chemistry) is a technical course that teaches students about the principles and techniques of Spaking English. The Maharashtra State Board of Technical Education (MSBTE) conducts exams for this course as part of the assessment process for students pursuing technical education in Maharashtra, India. In this article, we will discuss some of the important questions that students can expect to encounter in the MSBTE Basic Science Chemistry exams.
The Maharashtra State Board of Technical Education (MSBTE) conducts exams for technical courses offered by various institutes in the state of Maharashtra, India. These exams are an important part of the assessment process for students pursuing technical education. In this article, we will discuss some of the important questions that students can expect to encounter in the MSBTE exams.
1. What is the structure of the MSBTE exams?
The MSBTE exams are typically divided into two parts: the theory exams and the practical exams. The theory exams cover the theoretical concepts taught in the course, while the practical exams test the students' practical skills and knowledge.
2. What is the format of the MSBTE exams?
The MSBTE exams are usually multiple choice questions (MCQs), where students have to select the correct answer from a list of options. Some exams may also have short-answer or long-answer questions.
3. What are the important topics covered in the MSBTE exams?
The important topics covered in the MSBTE exams depend on the course being studied. Some common topics that may be covered include mathematics, physics, chemistry, engineering, computer science, and electronics.
4. How can students prepare for the MSBTE exams?
There are several ways that students can prepare for the MSBTE exams:
Review the course material and make a study plan: It is important to review all the topics covered in the course and make a plan to cover them before the exams.
Practice previous year's question papers: Solving previous year's question papers can help students get an idea of the types of questions that may be asked in the exams.
Attend coaching classes: Many institutes offer coaching classes to help students prepare for the exams. These classes can be helpful in clearing doubts and providing guidance on exam preparation.
Take online practice tests: There are several websites and apps that offer online practice tests for the MSBTE exams. These tests can help students assess their knowledge and identify their strengths and weaknesses.
The passing mark for the MSBTE exams is 40%. This means that students must score at least 40% in each subject to pass the exam.
In conclusion, the MSBTE exams are an important part of the technical education assessment process in Maharashtra, India. Students can prepare for the exams by reviewing the course material, practising previous year's question papers, attending coaching classes, and taking online practice tests. The passing mark for the exams is 40%.
| Program: Diploma in Engineering (All Branches) |
|---|
| Program Code:- CE/CO/EE/EJ/ME |
| Scheme:- I |
| Semester:- 1 |
| Course:- Basic Chemistry |
| Course Code:- 22102 |
04 – CHEMICAL BONDING AND CATALYSIS
Q 1. Metals lose electrons from their lattice to become ……….
A. Positive ions B. Negative ions
C. Alkalies D. Non-metals
Answer: - Option A
Explanation: - Metal losses electrons and become positive charged ion.
Q 2. Dative Covalent bond is found in ………
A. Ammonia B. Ammonium ion
C. Urea D. Nitrogen
Answer: - Option B
Explanation: - Ammonium ion contains dative bond (NH4+)
Q 3. Charge on any ion depends upon gain or loss of ………
A. Electrons B. Protons
C. Neutrons D. Nucleons
Answer: - Option A
Explanation: - When an atom losses or gains electrons, it will convert into charged ions.
Q 4. Metals and Non- metals combine to give electronic configuration of ……….
A. Alkalies B. Noble gases
C. Metalloids D. Acids
Answer: - Option B
Explanation: - When metals and non- metals loss and gain electrons respectively, their electronic configuration will become as noble gases.
Q 5. Noble gases exist as ……………
A. Monoatomic B. Diatomic
C. Polyatomic D. None of these
Answer: - Option A
Explanation: - Noble gases are stable so they exist as monoatomic.
Q 6. When magnesium reacts with oxygen, nature of the bond formed is ……….
A. Ionic B. Covalent
C. Metallic D. Dative
Answer: - Option A
Explanation: - Magnesium Oxide (MgO) has ionic bond.
Q 7. Metals are good conductors due to ………
A. Ionic lattice B. Crystalline lumps
C. Mostly solids D. Delocalized electrons.
Answer: - Option D
Explanation: - Metals are good conductors due to delocalized electrons means moving electrons.
Q 8. When a covalent bond is formed between hydrogen atom and a very electronegative atom, then it is known as……
A. Ionic bond B. Hydrogen bond
C. Co-ordinate bond D. All of the above
Answer: - Option B
Explanation: - Bond formed between hydrogen and very electronegative atom (O, N, F) is known as hydrogen bonding
Q.9. Molecules which have permanent dipole are known as………
A. Polar B. Dipole
C. Non-polar D. Tripolar
Answer: - Option A
Explanation: - Molecules which have permanent dipole are known as polar like H-Cl, H-F
Q 10. Electrovalent bond is another name of ………….
A. Metallic bond B. Covalent bond
C. Ionic bond D. Co-ordinate bond
Answer: - Option C
Explanation: - Electrovalent bond is another name of Ionic bond.
11. Covalent compounds are …………….
A. Good conductors of electricity B. Non-conductors of electricity
C. Poor conductors of electricity D. None of the above
Answer: - Option B
Explanation: - Covalent compounds don't split into ions when dissolved due that covalent compounds are non-conductors of electricity.
12. Crystal lattice is actually …………
A. Sum of points B. Array of points
C. Lines of points D. triangles of points
Answer: - Option A
Explanation: - Crystal lattice is array of points due to the ordered internal arrangement of atoms in a crystal structure
13. Unit cell is the smallest building unit of ………………
A. Crystal lattice B. Liquids
C. Gases D. None of the above
Answer: - Option A
Explanation: - Unit cell is the smallest building unit of crystal lattice.
14. Which of the following is an amorphous solid?
A. Diamond B. Glass
C. Sodium chloride D. None of the above
Answer: - Option B
Explanation: - Glass is an amorphous solid because Silicon dioxide molecules are not packed in a crystal lattice
The co-ordinate number of FCC structure is…………..
A. 4 B. 8
C. 2 D.12
Answer: - Option 12B
1. Explanation: - FCC coordination number is 12. Coordination number is the number of atoms or ions immediately surrounding a central atom in a complex or crystal.
The lattice site in a pure crystal cannot be occupied by ……………
A. Molecule B. Ion
C. Electron D. Atom
Answer: - Option C
Explanation: - The lattice site in a pure crystal can be occupied by molecule, ion or atom.
Substance which alter the rate of chemical reaction without undergoing any chemical change are called as ………
A. Polymers B. catalysts
C. Products D. None of the above
Answer: - Option B
Explanation: - Substance which alter the rate of chemical reaction without undergoing any chemical change are called as catalysts.
The substance that reduce the effectiveness of a catalyst are called ………
A. Promoters B. Autocatalysts
C. Inhibitors D. None of the above.
Answer: - Option C
Explanation: - The substance that reduce the effectiveness of a catalyst are called inhibitors.
When catalyst and reactant are in the same phase then it is called…….
A. Heterogenous catalysis B. Homogenous catalysis
C. Autocatalysis D. None of these
Answer: - Option B
Explanation: - When catalyst and reactant are in the same phase then it is called homogenous catalysis.
When a product acts as a catalyst then it is called as ……….
A. Self-catalysis B. Positive catalysis
C. Autocatalysis D. Negative catalysis
Answer: - Option C
Explanation: - Single chemical reaction is said to be autocatalytic if one of the reaction products is also a catalyst for the same or a coupled reaction.
Complete transfer of one or more electrons between atoms constituting in forming…………
A. Ionic Bond B. Covalent bond
C. Co-ordinate Bond D. Dative Bond
Answer: - Option A
Explanation: - Ionic bond is formed by complete transfer of one or more electrons.
When a single atom provides both electrons which are needed for completion of covalent bond then it leads to……
A. Ionic Bond B. Covalent bond
C. Co-ordinate Bond D. None
Answer: - Option C
Explanation: - A coordinate bond (also called a dative covalent bond) is a covalent bond (a shared pair of electrons) in which both electrons come from the same atom.
In ammonia ion, electrons required between hydrogen ion and nitrogen ion are…………
A. 1 B. 2
C. 3 D. 4
Answer: - Option B
Explanation: - In ammonia ion, electrons required between hydrogen ion and nitrogen ion are 2.
Pairs of outer shell electrons not used in bonding are called as………
A. Valence electrons B. Donor electrons
C. Electrovalent electrons D. Lone pairs
Answer: - Option D
Explanation: - A lone pair is an electron pair in the outermost shell of an atom that is not shared or bonded to another atom.
Bond formed by sharing of four electrons is called as……………….
A. Covalent bond B. Electrovalent bond
C. Dative covalent bond D. Double covalent bond
Answer: - Option D
Explanation: - Bond formed by sharing of four electrons is called as double covalent bond. (E.g. O2, CO)
For dative covalent bonding, one atom having a lone pair of electrons combines with …
A. An electron deficient compound B. An expanded octet
C. A proton of other atom D. A neutron of other atom
Answer: - Option A
Explanation: - For dative covalent bonding, one atom having a lone pair of electrons combines with an electron deficient compound.
When the bond is formed by sharing of two pairs of electrons by atoms, then the bond is called as……..
A. Single covalent bond B. Double covalent bond
C. Triple covalent bond D. Ionic bond
Answer: - Option B
Explanation: - When the bond is formed by sharing of two pairs of electrons by atoms, then the bond is called as double covalent bond. (E.g. O2, CO)
Neither ions nor electrons are free to move in………………
A. Liquids B. Metals
C. Ionic solids D. All of the above
Answer: - Option C
Explanation: - Neither ions nor electrons are free to move in ionic solids.
Weak forces between molecules are called as………………………
A. Molecular forces B. Intermolecular forces
C. Intramolecular forces D. Extramolecular forces
Answer: - Option B
Explanation: - Weak forces between molecules are called as Intermolecular forces.
Electrons are usually lost by…………………………….
A. Metals B. Non-metals
C. Inert gases D. All of the above
Answer: - Option A
Explanation: - Electrons are usually lost by Metal.
In nitrogen molecule, numbers of electrons required by each nitrogen atom in outer shell are……………..
A. 1 B. 2
C. 3 D. 4
Answer: - Option C
Explanation: - Nitrogen atom has electronic configuration like (2, 5). So numbers of electrons required by each nitrogen atom in outer shell are 3.
Conduction of electricity in metallic bonding is due to the presence of……………
A. Protons B. Lattice
C. Delocalized electrons D. Nucleus
Answer: - Option C
Explanation: - Conduction of electricity in metallic bonding is due to the presence of delocalized electrons.
Metal atoms……………………
A. Lose their outer electrons B. Become positively charged
C. Become negatively charged D. Both (A) & (B)
Answer: - Option D
Explanation: - Metal losses electrons and become positive charged ion.
Nitrogen molecule is an example of ………………………….
A. Single covalent bond B. Double covalent bond
C. Triple covalent bond D. Single co-ordinate bond
Answer: - Option C
Explanation: - Nitrogen molecule is formed by sharing of three electron pairs.
Regular arrangement in which atoms are closely packed together is called a ……
A. Tetrahedral structure B. Lattice
C. Crystal lattice D. Ionic bond
Answer: - Option C
Explanation: - Regular arrangement in which atoms are closely packed together is called a Crystal lattice.
Resulting a loss of electrons forms …………………………………
A. Anodes B. Cathodes
C. Negative ions D. Positive ions
Answer: - Option D
Explanation: - When an atom losses electrons form positive ions.
Representation of bond by single, double or triple line is done in…………………
A. Metallic bond B. Co-ordinate bond
C. Covalent bond D. Ionic bond
Answer: - Option C
Explanation: - Covalent bonding has three types of bonding like single ,double & triple covalent bond.
Which of the following characteristic does not possess by the metal?
A. Luster B. Ductility
C. Increase in conductance by increase in temperature D. Malleability
Answer: - Option C
Explanation: - Increase in conductance by increase in temperature. For metals, the thermal conductivity is mainly a function of the motion of free electrons.
On which factor, conductance of metals is responsible?
A. Ions B. Delocalized electrons
C. Atomic kernel D. Number of atoms
Answer: - Option B
Explanation: - For metals, the thermal conductivity is mainly a function of the motion of free electrons i.e. delocalized electrons.
The difference between the number of atoms in a unit cell of a BCC crystal and an FCC crystal is ………….
A. 1 B. 2
C. 4 D. 6
Answer: - Option B
Explanation: - The number of atoms in a unit cell of a BCC crystal is 2 and an FCC crystal is 4. So the difference between two is 2.
When partial positive end of one molecule is attracted weakly to partial negative end , then the force between them is…………………….
A. Electrostatic force B. Dipole – dipole interaction
C. Ionic bond D. None of the above
Answer: - Option B
Explanation: - partial positive end of one molecule is attracted weakly to partial negative end , then the force between them is dipole – dipole interaction
Tendency of atoms to acquire eight electrons in their valence shell is…………. …
A. Octet rule B. Duplet rule
C. Triplet rule D. All of the above
Answer: - Option A
Explanation: - Tendency of atoms to acquire eight electrons in their valence shell or last orbit is octet rule.
E.g. Mg Mg ++ + 2e- (2 , 8, 2) (2 , 8)
In the formation of Mg++ ion. Which one is the correct reaction in the following?
A. Mg → Mg++ + 4e- B. Mg → Mg++ + 2e-
C. Mg → Mg++ + 3e- D. Mg → Mg++ + 1e-
Answer: - Option B
Explanation: - Mg Mg ++ + 2e-
(2 , 8, 2) (2 , 8)
What type of bond form between hydrogen & oxygen atom in the given structure?
A . Hydrogen Bond B. Metallic Bond
C. Non-metallic Bond D. Oxygen Bond
Answer: - Option A
Explanation: - The hydrogen bond is an attractive interaction between a hydrogen atom from a molecule or a molecular fragment X–H in which X is more electronegative atom like O, N, F.
The given figure represents
A. Non-Metal sea model B. Cation sea model
C. Electron sea model D. Bohr’s atomic model
Answer: - Option C
Explanation: - The electron sea model is a model of metallic bonding in which cations (positive-charged metal ions) are considered to be fixed points within a mobile 'sea' of electrons.
What type of interaction between δ+ & δ- ?
A. Positive negative B. Chargeable
C. Dipole-dipole D. Equal
Answer: - Option C
Explanation: - Two hydrogen chloride molecules displaying dipole-dipole interaction The relatively negative chlorine atom is attracted to the relatively positive hydrogen atom.
The catalyst used in the lead chamber process of sulphuric acid manufacturing
A. Platinum B. Oxide of nitrogen
C. Nickel D. Vanadium compound
Answer: - Option B
Explanation: - Lead-chamber Process, method of producing sulfuric acid by oxidizing sulfur dioxide with moist air, using gaseous nitrogen oxides as catalysts, the reaction taking place primarily in a series of large, boxlike chambers of sheet lead.
An example of autocatalytic reaction is …
A. The decomposition of nitroglycerine B. Thermal decomposition of KClO3 & MnO2 mixture
C. Break down of 6C14 D. Hydrogenation of vegetable oil using nickel catalysts
Answer: - Option A
Explanation: - N2 is one of the product of decomposition of nitroglycerine plays the role of an autocatalyst.
The coordination number of a metal crystallizing in a hexagonal close packing (HCP) structure is
A. 6 B. 7
C. 8 D. 12
Answer: - Option D
Explanation: - The number of the nearest atoms surrounded by an atom is called the coordination number of that lattice. The coordination number of the hexagonal close-packed structure is 12.
Which of the following compound possesses covalent bond?
A. CaCl2 B. BaCl2
C. AlCl3 D. H2O
Answer: - Option D
Explanation: - H2O has single covalent bond
Proton accelerate the hydrolysis of ester. This is an example of ………
A. A Heterogenous catalysis B. An acid-base catalysis
C. A promoter D. A negative catalyst
Answer: - Option B
Explanation: - In hydrolysis of ester, acid forms and hydrogen ion (proton) acts as a catalyst. So, this is a example of acid-base catalyst.
Which of the following processes does not involve a catalyst?
A. Haber’s process B. Thermite process
C. Ostwald process D. Contact process
Answer: - Option B
Explanation: - The Thermite Process or Goldschmidt Process is the method of obtaining liquid metal by reduction of the oxide with aluminium powder, when ignited with magnesium ribbon it reacts by producing iron and aluminium oxide at an intensely high temperature approaching 3000oC. The reducing agent is aluminium.
Which of the following reaction is catalysed by enzyme maltase?
A. Starch to maltose B. Maltose to Glucose
C. Lactose to maltose D. Maltose to glucose + Fructose
Answer: - Option B
Explanation: - The enzyme which converts maltose to glucose is maltase.
The transition metal used as a catalyst is…..
A. Nickel B. Platinum
C. Cobalt D. All of these
Answer: - Option D
Explanation: - The transition metals used as a catalyst are Ni, Co, Pt, Cd etc
In the Ostwald’s process for the manufacture of HNO3, the catalyst used is……
A. Mo B. Fe
C. Ni D. Pt
Answer: - Option D
Explanation: - In the Ostwald’s process for the manufacture of HNO3, the catalyst used is Pt.
Adam’s catalyst is …
A. Platinum B. Iron
C. Molybdenum D. Nickel
Answer: - Option A
Explanation: - Adam’s catalyst, also known as platinum dioxide, is usually represented as Platinum(IV) oxide hydrate, PtO2•H2O.
Which of the following is not a category of catalysis?
A. Homogeneous B. Heterogeneous
C. Artificial D. Enzymatic
Answer: - Option C
Explanation: - Homogeneous, Heterogeneous and Enzymatic are categories of catalysis.
Which of the following is an example of homogeneous catalysis ?
A. Enzyme catalysis B. Hardening of animal and vegetable oils
C. Haber’s process D. Cracking of heavy oils for synthesis of gasoline
Answer: - Option A
Explanation: - Enzymes are homogeneous catalysts since they have to be in the same state as that of the reactants in order to mix well and speed up the decomposition of the biomolecule.
Which of the following statement is incorrect about the adsorption theory?
A. The catalyst is more efficient in finely divided state B. Action of promoters is not explained
C. Enhanced activity of a rough surface catalyst is explained D. Specific action of catalyst is explained
Answer: - Option B
Explanation: - Action of promoter is not related to the adsorption theory.
Which of the following process used for preparation of sulphuric acid?
A. Ostwald;s process B. Bergius process
C. Deacon’s process D. Chamber process
Answer: - Option D
Explanation: - Both Chamber process and Contact process are used for preparation of sulphuric acid.
Select the catalyst which is used for manufacturing of ethanol from glucose
A. Maltose B. Pt/V2O5
C. Zymase D. Fe2O3
Answer: - Option C
Explanation: - Glucose is converted to ethanol by the action of yeast Zymase.
Which of the following process is used for the preparation of Chlorine gas?
A. Deacon’s process B. Bergius process
C. Ostwald’s process D. Haber’s process
Answer: - Option A
Explanation: - Preparation of chlorine in Deacon's process: Atmospheric oxygen oxidizes HCl gas in presence of cupric chloride catalyst to form chlorine. Temperature is 723 K.
4Cl + O2 CuCl2 2Cl2 + 2H2O
Name the catalyst which is used For manufacture of glucose from cane sugar.
A. Maltase B. Zymase
C.CuCl2 D. CuCl
Answer: - Option A
Explanation: - Glucose is converted to cane sugar by the action of maltase.
Name the metal which increase the activity of iron metal when added in small amount.
A. Cu B. Mo
C. Al D. Mn
Answer: - Option B
Explanation: - Mo increases the activity of iron metal when added in small amount.
What is the role of Mo in following reaction:
A. Catalytic inhibitor B. Catalytic promoter
C. Catalyst D. Auto catalyst
Answer: - Option B
Explanation: - Ammonia industrially synthesized by the Haber-Bosch process from nitrogen gas and hydrogen gas in the presence of an iron-based catalyst. Electron transfer was taking place between two molybdenum atoms linked by a nitrogen molecule. Here Mo acts as catalytic promoter.
The adsorption theory is applicable to …
A. Homogeneous catalysis B. Heterogeneous catalysis
C. Catalysis D. None of the above
Answer: - Option B
Explanation: - Adsorption theory is applicable for solid catalysts which show heterogeneous catalysis. According to this theory, the gaseous reactants are adsorbed in the surface of the solid catalyst.
Water accumulates in cells of animals and plants due to presence of …
A. Covalent bond B. Co-ordinate bond
C. Hydrogen bond D. Electrovalent bond
Answer: - Option C
Explanation: - Water accumulates in cells of animals and plants due to presence of Hydrogen bond.
Solid CO2 is an example of…….
A. Molecular crystal B. Ionic crystal
C. Covalent crystal D. Metallic crystal
Answer: - Option A
Explanation: - Solid CO2 is an example of Molecular crystal. They have relatively weak intermolecular binding.
Which of the following is Amorphous?
A. Polystyrene B. Table salt
C. Silica D. Diamond
Answer: - Option C
Explanation: - The amorphous form of silica has been used as a photovoltaic solar cell because this is lightweight & flexible.
The property of crystalline solid is not
A. Anisotropic B. Isotropic
C. Hard D. Dense
Answer: - Option B
Explanation: Isotropic materials are materials whose properties remain the same when tested in different directions. The crystalline solids are anisotropic in nature, this means that the physical properties do change with the change in direction.
Characteristics features of solids are
A. Definite shape B. Definite size
C. Definite shape and size D. definite shape and rigidity
Answer: - Option D
Explanation: - Definite shape and rigidity are the characteristics features of solids.
Diamond is an example of
A. Solid with hydrogen bonding B. Electrovalent solid
C. Covalent solid D. Glass
Answer: - Option C
Explanation: - Diamond is a covalent solid and yet has a high melting point mainly due to its interlinked structure.
Which solid will have the weakest inter molecular forces?
A. Ice B. Phosphorus
C. Naphthalene D. Sodium Fluoride
Answer: - Option A
Explanation: - Ice has the lowest melting point out of the given solids , hence it has the weakest intermolecular forces.
Which of the following example of metallic crystal solid
A. C B. Si
C. W D. AgCl
Answer: - Option A
Explanation: - Metallic crystals consists of metal cations surrounded by large number of mobile valence electrons, these electrons are also known as delocalised electrons, which do not belong to any one atom, but are capable of moving through the crystal. As a result metallic crystals are good conductors of electricity. E.g. Au, W etc
Lead is a metallic crystal having a structure.
A. FCC B. BCC
C. HCP D. TCP
Answer: - Option A
Explanation: - Crystalline solids are classified as either metallic or non-metallic. Pb, along with Cu, Ag, Al, and Ni, has a face-centered cubic structure.
Which of the following has a HCP crystal structure?
A. W B. Mo
C. Cr D. Zr
Answer: - Option D
Explanation: - Crystalline solids are classified as either metallic or non-metallic. W, Mo, and Cr are examples of the body-centered cubic structure of crystals. The HCP structure is found in Mg, Zn, Ti, Cd, Zr, and others.
Amorphous solids have structure.
A. Regular B. Linear
C. Irregular D. Dendritic
Answer: - Option C
Explanation: - Materials in which the molecule is the basic structural solid and has an irregular structure is known as amorphous solid. Crystalline solids, on the other hand, usually are arranged in a regular manner.
Bravais lattice consists of space lattices.
A. Eleven B. Twelve
C. Thirteen D. Fourteen
Answer: - Option D
Explanation: - Materials in which the molecule is the basic structural solid and has an irregular structure is known as amorphous solid. Crystalline solids, on the other hand, usually are arranged in a regular manner.
Identify the lattice structure of given unit cell;
A. SCC B. BCC
C. FCC D. HCP
Answer: - Option B
Explanation: - Some metals crystallize in an arrangement that has a cubic unit cell with atoms at all of the corners and an atom in the center, This is called a body-centered cubic (BCC) solid.
Identify the lattice structure of given unit cell;
A. SCC B. BCC
C. FCC D. HCP
Answer: - Option C
Explanation: - Metal crystallize in an arrangement that has a cubic unit cell with atoms at all of the corners and at the centers of each face, This arrangement is called a face-centered cubic (FCC) solid.
Identify the lattice structure of given unit cell;
A. SCC B. BCC
C. FCC D. HCP
Answer: - Option A
Explanation: - In a simple cubic lattice, the unit cell that repeats in all directions is a cube defined by the centers of eight atoms.
The coordination number of a metal crystal in a Simple Cubic (SC) structure is
A. 6 B. 7
C. 8 D. 12
Answer: - Option A
Explanation: - The number of the nearest atoms surrounded by an atom is called the coordination number of that lattice. The coordination number of the simple cubic structure is 6.
The coordination number of a metal crystal in a Body centered cubic (BCC) structure is
A. 6 B. 7
C. 8 D. 12
Answer: - Option C
Explanation: - The number of the nearest atoms surrounded by an atom is called the coordination number of that lattice. The coordination number of the body centered cubic structure is 8.