Some Basic Concepts of Chemistry

The right option for the mass of CO2 produced by heating 20 g of 20\% pure limestone is (Atomic mass of Ca = 40) [ CaCO3 1200 K CaO + CO2]

1. 1.76 g
2. 2.64 g
3. 1.32 g
4. 1.12 g

In one molal solution that contains 0.5 mole of a solute, there is

1. 500 mL of solvent
2. 500 g of solvent
3. 100 mL of solvent
4. 1000 g of solvent

What mass of 95% pure CaCO3 will be required to neutralise 50 mL of 0.5 M HCl solution according to the following reaction? CaCO3(s) + 2HCl(aq) CaCl2(aq) + CO2(g) + 2H2O(l) [Calculate upto second place of decimal point]

1. 1.25 g
2. 1.32 g
3. 3.65 g
4. 9.50 g

The density of the solution is 2.15 g mL-1, then mass of 2.5 mL solution in correct significant figures is :

1. 53.75 g
2. 5375 10-3 g
3. 5.4 g
4. 5.38 g

An organic compound contains 78% (by wt.) carbon and remaining percentage of hydrogen. The right option for the empirical formula of this compound is : [Atomic wt. of C is 12, H is 1]

1. CH4
2. CH
3. CH2
4. CH3

Which one of the following has maximum number of atoms?

1. 1 g of Mg(s) [Atomic mass of Mg = 24]
2. 1 g of O2(g) [Atomic mass of O = 16]
3. 1 g of Li(s) [Atomic mass of Li = 7]
4. 1 g of Ag(s) [Atomic mass of Ag = 108]

The number of moles of hydrogen molecules required to produce 20 moles of ammonia through Haber’s process is :

1. 10
2. 20
3. 30
4. 40

A mixture of 2.3 g formic acid and 4.5 g oxalic acid is treated with conc. H2SO4. The evolved gaseous mixture is passed through KOH pellets. Weight (in g) of the remaining product at STP will be

1. 1.4
2. 3.0
3. 2.8
4. 4.4

In which case is number of molecules of water maximum?

1. 18 mL of water
2. 0.18 g of water
3. 0.00224 L of water vapours at 1 atm and 273 K
4. 10-3 mol of water

Suppose the elements X and Y combine to form two compounds XY2 and X3Y2. When 0.1 mole of XY2 weighs 10 g and 0.05 mole of X3Y2 weighs 9 g, the atomic weights of X and Y are

1. 40, 30
2. 60, 40
3. 20, 30
4. 30, 20