Read the following passage and answer the questions.

Suppose there is a market consisting of identical firms producing the same quality of salt.

Suppose the market demand curve and the market supply curve for salt are given by:

$Q_D=350-p$ for $0 ≤ p ≤ 350$

= 0 for p > 350

$Q_S = 220 + p$ for $p ≥ 10$

= 0 for 0 ≤ p < 10

Where $Q_D$ and $Q_S$ denote the demand for and supply of salt (in kg) respectively and p denotes the price of salt per kg in rupees.

If the government imposes a price ceiling of Rs 31 on salt, what will be the volume of excess demand/ supply in the market?

Excess demand of 68 units.

The correct answer is Option (1) → Excess demand of 68 units. 

$Q_D=350 - p$

$Q_S = 220 + p$

Price ceiling p=31

$Q_D= 350 -31 = 319

$Q_S = 220 + 31 = 251

Excess Demand= 319 - 251 = 68