10th Science Book Back Answers Unit 7 – Atoms And Molecules:
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Samacheer Kalvi 10th Science Book Back Answers Chemistry Unit 7 – Atoms And Molecules:
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10th Science – Chemistry
Unit 7: Atoms And Molecules
I. Choose the best answer:
1. Which of the following has the smallest mass?
a) 6.023 × 1023 atoms of He b) 1 atom of He
c) 2 g of He d) 1 mole atoms of He
Ans : (b) 1 atom of He
2. Which of the following is a triatomic molecule?
a) Glucose b) Helium c) Carbon dioxide d) Hydrogen
Ans : (c) Carbon dioxide
3. The volume occupied by 4.4 g of CO2 at S.T.P
a) 22.4 litre b) 2.24 litre c) 0.24 litre d) 0.1 litre
Ans : (b) 2.24 litre
4. Mass of 1 mole of Nitrogen atom is
a) 28 amu b) 14 amu c) 28 g d) 14 g
Ans : (c) 28 g
5. Which of the following represents 1 amu?
a) Mass of a C – 12 atom b) Mass of a hydrogen atom
c) 1/12th of the mass of a C – 12 atom d) Mass of O – 16 atom
Ans : (c) 1/12th of the mass of C – 12 atom
6. Which of the following statement is incorrect?
a) One gram of C – 12 contains Avogadro’s number of atoms.
b) One mole of oxygen gas contains Avogadro’s number of molecules.
c) One mole of hydrogen gas contains Avogadro’s number of atoms.
d) One mole of electrons stands for 6.023 × 1023 electrons.
Ans : (d) One mole of electrons stands for 6.023 × 1023 electrons.
7. The volume occupied by 1 mole of a diatomic gas at S.T.P is
a) 11.2 litre b) 5.6 litre c) 22.4 litre d) 44.8 litre
Ans : (c) 22.4 litre
8. In the nucleus of 20Ca40, there are
a) 20 protons and 40 neutrons b) 20 protons and 20 neutrons
c) 20 protons and 40 electrons d) 40 protons and 20 electrons
Ans : (b) 20 protons and 20 neutrons
9. The gram molecular mass of oxygen molecule is
a) 16 g b) 18 g c) 32 g d) 17 g
Ans : (c) 32 g
10. 1 mole of any substance contains molecules.
a) 6.023 × 1023 b) 6.023 × 10-23 c) 3.0115 × 1023 d)12.046 × 1023
Ans : (a) 6.023 × 1023
II. Fill in the blanks:
1. Atoms of different elements have a mass numbers, but atomic numbers are called isobars. Ans: same, different
2. Atoms of different elements having same number of are called isotones. Ans: neutrons
3. Atoms of one element can be transmuted into atoms of other elements by _______.
Ans : artificial transmutation
4. The sum of the numbers of protons and neutrons of an atom is called its. Ans: Mass number
5. Relative atomic mass is otherwise known as . Ans: Standard atomic weight
6. The average atomic mass of hydrogen is amu. Ans: 1.008
7. If a molecule is made of similar kind of atoms, then it is called atomic molecule. Ans : Homo
8. The number of atoms present in a molecule is called its _______. Ans: Atomicity
9. One mole of any gas occupies ml at S.T.P. Ans: 22400
10. Atomicity of phosphorous is ______. Ans: 4
III. Match the following:
Question
| a. 8 g of O2 | i. 4 moles |
| b. 4 g of H2 | ii. 0.25 moles |
| c. 52 g of He | iii. 2 moles |
| d. 112 g of N2 | iv. 0.5 moles |
| e. 35.5 g of Cl2 | v. 13 moles |
Answer:
a – ii, b – iii, c – v, d – i, e – iv.
III. True or False (Correct the Statement if it is false)
1. Two elements sometimes can form more than one compound. Ans: True.
2. Noble gases are Diatomic. Ans: False. Monoatomic.
3. The gram atomic mass of an element has no unit.
Ans: False. The relative atomic mass of an element has no unit.
4. 1 mole of Gold and Silver contains the same number of atoms. Ans: True.
5. Molar mass of CO2 is 42g. Ans: False. 44 g.
V. Assertion and Reason
Answer the following questions using the data given below:
a) A and R are correct, R explains the A.
b) A is correct, R is wrong.
c) A is wrong, and R is correct.
d) A and R are correct, R doesn’t explain A.
1. Assertion: Atomic mass of aluminum is 27
Reason: An atom of aluminum is 27 times heavier than 1/12th of the mass of the C – 12 atom.
Ans : (d) A and R are correct, R doesn’t explain A
2. Assertion: The Relative Molecular Mass of Chlorine is 35.5a.m.u.
Reason: The natural abundance of Chlorine isotopes are not equal.
Ans : (a) A and R are correct, R explains the A
Other Important links for 10th Science Book Answers Solutions:
For the 10th Standard Science Unit 8 book back question and answers solutions PDF, check the link – Samacheer kalvi 10th Science Unit 8 – Periodic Classification Of Elements
Click here for the complete Samacheer Kalvi 10th Science Book Back Solution Guide PDF – 10th Science Book Back Solutions