Atoms and Molecules Worksheets





Atoms and Molecules worksheets

The atom is a unit of matter which contains dense central nucleus inclosed within a cloud of negatively charged electrons. Atomic nucleus contains positively charged protons and electrically neutral charged neutron. Atom is classified according to the number of protons and neutrons present in its nucleus.

A molecule can be defined as a group of at least two atoms which are electrically neutral and are hold together by covalent chemical bonds.

Here you can find some objective questions and their answer related to atom and molecules. The answers of the questions are given at the bottom of the page.

Worksheet Questions:-

1. The weight  of 10 \times 10^{22} molecules of CuSO_4.5H_O is:

(a)    41.42 g

(b)   42.42 g

(c)    44.44 g

(d)   48.94 g

 

2. If the density of H_2O is 1 gm cm^{-3} then the volume of occupied by one molecule of H_O is nearly?

(a)    6.02 \times 10^{23} cm^3

(b)   3.02 \times 10^{23} cm^3

(c)    3.0 \times 10^{-23} cm^3

(d)   6.02 \times 10^{-23} cm^3

 

3. The formula weight of an acid is 82.0. in a titration 100 cm3 of a solution of this acid containing 39.0 g of the acid per litre were completely neutralized by 95.0 cm3 of aqueous NaOH containing 40.0 g of NaOH per litre. What is the basicity of the acid?

(a)    2

(b)   3

(c)    1

(d)   4

 

4. An aqueous solution of 6.3 g of acid dehydrate is made upto 250 ml. the volume of 0.1 N NaOH required to completely neutralize 10 ml of this solution is:

(a)    40 ml

(b)   30 ml

(c)    100 ml

(d)   4 ml

 

5. How many moles of electrons weight one kilogram? Mass of electron = (9.108 \times 10^{-31} kg, Avogadro number =  6.023 \times 10^{23})

(a)    6.023 \times 10^{22}

(b)   \dfrac{1}{9.108} \times 10^{31}

(c)    \dfrac{6.023}{9.108} \times 10^{54}

(d)   \dfrac{1}{9.108 \times 6.023}\times 10^8

 

6. Which has maximum number of atoms?

(a)    24 g of C (12)

(b)   56 g of Fe (56)

(c)    27 g of Al (27)

(d)   108 g of Ag (108)

 

7. The mass of nitrogen per gram hydrogen in the compound hydrazine is exactly one and half times the mass of nitrogen in the compound ammonia. The fact illustrates:

(a)    The law of conservation of mass

(b)   The multiple valency of nitrogen

(c)    The law of multiple proportions

(d)   The law of definite proportions

 

8. The ratio of amounts of H_2O needed to precipitate all the metal ions from 100 ml if 1 M AgNO_3 and 100 ml of 1 M CuSO_4 will be:

(a)    1 : 1

(b)   1 :2

(c)    2 : 1

(d)   None

 

9. The mass of carbon present in 0.5 mole of K_4[Fe(CN)_6] is:

(a)    1. 86 g

(b)   18 g

(c)    3. 62 g

(d)   36 g

 

10. Mass of a mole of electrons is:

(a)    0.206 mg

(b)   0.022 mg

(c)    0.55 mg

(d)   1.006 mg

 

11. A weight lifter after competition, drinks 500 of 9% glucose (mol. Wt = 180) solution. The number of glucose molecules taken by him are:

(a)    3.5 \times 10^{23}

(b)   1.5 \times 10^{23}

(c)    7.5 \times 10^{20}

(d)   8.0 \times 10^{18}

 

12. The hydrated salt  Na_2SO_4.n H_2O on heating losses 55.9% weight and becomes anhydrous. The value of n is:

(a)    10

(b)   15

(c)    8

(d)   9

 

13. The element whose one atom has a mass of 6.642 \times 10^{-26} kg is:

(a)    Silver

(b)   Calcium

(c)    Zinc

(d)   Cadmium

 

14. 13.5 g of Aluminium when changes to Al^{+3} ion in solution, will lose:

(a)    18.06 \times 10^{26} electrons

(b)   6.02 \times 10^{20} electrons

(c)    3.06 \times 10^{22} electrons

(d)   9.033 \times 10^{23} electrons

 

15. Atoms can accept energy only in discrete amounts is a statement of:

(a)    Frank-Hertz principle

(b)   Bohr-Burry rule

(c)    Compton effect

(d)   None of these

 

16. The molality of 90 % H_2 So_4 solution having a density of 1.80 g/ml is:

(a)    91. 8

(b)   46.66

(c)    9.18

(d)   23.46

 

17. How many moles of KMnO_4 will react with 1 mole of ferrous oxalate in acidic medium?

(a)    1/5

(b)   2/5

(c)    3/5

(d)   4/5

 

18. One mole of KClO_3 is thermally decomposed and the oxygen evolved is utilised to oxidize carbon into CO_2. The number of moles of CO_2 obtained is:

(a)    1.9

(b)   1.5

(c)    2.5

(d)   3.2

 

19. 208 g of BaCl_2 are treated with 49 g of H_2SO_4. The amount of BaSO_4 (At. Mass of Ba = 137) obtained is:

(a)    116. 5 g

(b)   233 g

(c)    11.65 g

(d)   23.33 g

 

20. The number of atoms in 0.004 g of magnesium is close to:

(a)    24 \times 10^{26}

(b)   2 \times 10^{20}

(c)     10^{20}

(d)   6.02 \times 10^{23}

 

Worksheet Answers:-

1. (a)       2. (c)       3. (a)       4. (a)        5. (d)

6. (a)       7. (c)        8. (b)       9. (d)       10. (c)

11. (b)     12. (a)     13. (b)       14. (d)     15. (a)

16. (a)     17. (c)      18. (b)     19. (a)       20. (c)



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