Some Basic Concepts of Chemistry

250 mL of a sodium carbonate solution contains 2.65 g of Na₂CO₃. If 10 mL of this solution is diluted to one litre, what is the concentration of the resultant solution ?

• 0.1 M

• 0.001 M

• 0.01 M

• 10^-4 M

How many litres of oxygen (at STP) are required for complete combustion of 39 g of liquid benzene? (Atomic weights: C = 12, O = 16, H = 1).

• 84

• 22.4

• 42

• 11.2

X litre of carbon monoxide is present at STP. It is completely oxidized to CO₂. The volume of CO₂ formed is 11.207 litres. What is the value of X in litres?

• 22.414

• 11.207

• 5.6035

• 44.828

The concentration of a 100 mL solution containing X g of Na₂CO₃ (molecular wt. = 106) is Y M. The values of X and Y are respectively.

• 2.12, 0.05

• 1.06, 0.2

• 1.06, 0.1

• 2.12, 0.1

One mole of fluorine is reacted with two moles of hot concentrated KOH. The products formed are KF, H₂O and O₂. The molar ratio of KF, H₂O and O₂ , respectively is

• 1 : 1 : 2

• 2 : 1 : 0.5

• 1 : 2 : 1

• 2 : 1 : 2

The electrochemical equivalent of a metal is 'x' g coulomb^-1. The equivalent weight of metal is

• x

• x × 96500

• $\frac{\mathrm{x}}{96500}$

• 1.6 × 10¹⁹ × x

x grams of water is mixed in 69 g of ethanol. Mole fraction of ethanol in the resultant solution is 0.6. What is the value of x in grams?

• 54

• 36

• 180

• 18

An organic compound containing C and H has 92.3% of carbon. Its empirical formula is

• CH

• CH₃

• CH₂

• CH₄

x grams of calcium carbonate was completely burnt in air. The weight of the solid residue formed is 28 g. What is the value of x (in grams)?

• 44

• 200

• 150

• 50

The concentration of oxalic acid is 'x' mol L^-1. 40 mL of this solution reacts with 16 mL of 0.05 M acidified KMnO₄. What is the pH of 'x' M oxalic acid solution ? (Assume that oxalic acid dissociates completely)

• 1.3

• 1.699

• 1

• 2