Assignment-1 (Chemistry)----SOME BASIC CONCEPTS OF CHEMISTRY

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1. If N_A is Avogadro’s no. Then no. Of valence electrons in 4.2 g of nitride ions [N^3-] is

a. 4.2 NA

b. 2.4 NA

c. 1.6 NA

d. 3.2 NA

2. 1 amu is equal to

a. 1/14 of O-6

b. 1/12 of C-12

c. 1 g of H₂

d. 1.66×10^-23 kg

3. 60 g of organic compound on analysis gave following results. C=24g, H=4g and O=32g. The empirical formula of the compound is

a. CH₂O

b. CHO

c. C₂H₂O

d. C₂H₂O₂

4. Volume of gas at N.T.P is 1.12×10^-7 cc. The no. Of molecule in it is

a. 3.01×10¹²

b. 3.01×10¹⁸

c. 3.01×10²⁴

d. 3.01×10³⁰

5. The no. of atoms in 4.25 g of NH₃ is

a. 2.054×10²³

b. 3.034×10²³

c. 3.044×10²³

d. 6.022×10²³

6. 2 moles of C₂H₅OH burns excess of air to form CO₂

a. 88g

b. 176g

c. 44g

d. 22g

7. The product of atomic weight and specific heat of any element is a constant, approximately 6.4 this is known as

a. Dalton’s law

b. Avogadro’s law

c. Newton’s law

d. Dulong petit law

8. The vol of Cl₂ at STP obtained on reacting 4.35g MnO₂ with conc. HCl (At. Wt. Of Mn=55)

a. 4.48L

b. 2.24L

c. 1.12L

d. 0.56L

9. 5 moles of SO₂ and 5 moles of O₂ react to form SO₃. Only 60% SO₂ is used. The no. of moles left is

a. 6.5

b. 10

c. 8

d. 8.5

10. A cylinder of gas supplied by Bharat petroleum is assumed to contain 14g of butane. A normal family requires 20,000 KJ of energy per day for cooking, butane gas in cylinder lasts for___days (∆H_c of C₄H₁₀= -2658 kJ per mol)

a. 15 days

b. 20 days

c. 32 days

d. 40 days

11. No of moles of He in 100 moles of He are

a. 25

b. 100

c. 50

d. 1000000

12. In a compound C,H and N are present in 9:1:3:5 by weight. If molecular weight of the compound is 108, then molecular formula for that compound is

a. C₂H₆N₂

b. C₃H₄N

c. C₆H₈N₂

d. C₉H₁₂N₃

13. In redox rxn 1 gm-eq of reducing agent require P gm-eq of oxidising agent. The value of P is

a. 1

b. 2

c. 3

d. depends upon rxn

14. In a metal oxide, there is 20% O₂ by weight. Its equivalent weight is

a. 32

b. 40

c. 64

d. 72

15. What mass of Calcium chloride in grams would be enough to produce 14.35 g of AgCl?

a. 5.55gm

b. 8.295gm

c. 16.5g

d. 11.19g

16. Gastric juice contains 3.0 g of HCl per litre. If a person produces 2.5L of Gastric juice per day. How many antacid tablets each containing 400 mg of Al(OH)₃ are needed to neutralize all the HCl produced in one day

a. 18

b. 14

c. 20

d. 17

17. 7.36 g of a mixture of KCl and KI was dissolved in H₂O to prepare 1 L sol. 25 ml of this requires 8.45ml of 0.2N AgNO₃, what is % of KI in mixture?

a. 57.28

b. 47.28

c. 5.72

d. 49.12

18. The Hydrated salt Na₂Co₃.xH₂O undergoes 63% loss in mass on heating and becomes anhydrous. The value of x is

a. 10

b. 7

c. 5

d. 3

19. A compound made up of 2 elements A and B is found to contain 25% A and 75% B. The simplest formula for this is

a. AB

b. AB2

c. AB3

d. A3B

20. How much quick lime can be obtained from 25g of CaCO₃?

a. 18g

b. 14g

c. 28g

d. 34g