Some Basic Concepts of Chemistry · Question 34

25.3 g of sodium carbonate, Na2CO3 is dissolved in enough water to make 250 mL of solution. If sodium carbonate dissociates completely, molar concentration of sodium ion, Na+ and carbonate ions, CO32- are respectively (Molar mass of Na2CO3 = 106 g mol-1)

1. 0.955 M and 1.910 M
2. 1.910 M and 0.955 M
3. 1.90 M and 1.910 M
4. 0.477 M and 0.477 M

10 g of hydrogen and 64 g of oxygen were filled in a steel vessel and exploded. Amount of water produced in this reaction will be

1. 3 mol
2. 4 mol
3. 1 mol
4. 2 mol

What volume of oxygen gas (O2) measured at 0 C and 1 atm, is needed to burn completely 1 L of propane gas (C3H8) measured under the same conditions?

1. 5 L
2. 10 L
3. 7 L
4. 6 L

How many moles of lead (II) chloride will be formed from a reaction between 6.5 g of PbO and 3.2 g of HCl?

1. 0.011
2. 0.029
3. 0.044
4. 0.333

An organic compound contains carbon, hydrogen and oxygen. Its elemental analysis gave C, 38.71% and H, 9.67%. The empirical formula of the compound would be

1. CHO
2. CH4O
3. CH3O
4. CH2O

Volume occupied by one molecule of water (density = 1 g cm-3) is

1. 3.0 10-23 cm3
2. 5.5 10-23 cm3
3. 9.0 10-23 cm3
4. 6.023 10-23 cm3

An element, X has the following isotopic composition: 200X : 90\% 199X : 8.0\% 202X : 2.0\% The weighted average atomic mass of the naturally occurring element X is closest to

1. 201 amu
2. 202 amu
3. 199 amu
4. 200 amu

Concentrated aqueous sulphuric acid is 98% H2SO4 by mass and has a density of 1.80 g mL-1. Volume of acid required to make one litre of 0.1 M H2SO4 solution is

1. 16.65 mL
2. 22.20 mL
3. 5.55 mL
4. 11.10 mL

The maximum number of molecules is present in

1. 15 L of H2 gas at STP
2. 5 L of N2 gas at STP
3. 0.5 g of H2 gas
4. 10 g of O2 gas

In Haber process 30 litres of dihydrogen and 30 litres of dinitrogen were taken for reaction which yielded only 50% of the expected product. What will be the composition of gaseous mixture under the aforesaid condition in the end ?

1. 20 litres ammonia, 20 litres nitrogen, 20 litres hydrogen
2. 10 litres ammonia, 25 litres nitrogen, 15 litres hydrogen
3. 20 litres ammonia, 10 litres nitrogen, 30 litres hydrogen
4. 20 litres ammonia, 25 litres nitrogen, 15 litres hydrogen