Inflationary gap exists when Aggregate Demand is greater than Aggregate Supply at full employment.

Deficient demand refers to the situation when aggregate demand is short of aggregate supply corresponding to full employment level in the economy. Aggregate supply being perfectly elastic, it converges with aggregate demand at a lower level of output lower than the full employment level of output in the economy. This is a situation of underemployment equilibrium.

Aggregate supply refers to the desired level of output in the economy during an accounting year. It is through this output only that the producer sector generates income. 

Aggregate Demand refers to the desired level of expenditure in the economy during an accounting year. It is what people wish to spend on the purchase of goods and services during an accounting year.

Therefore, the point of  intersection between aggregate demand curve and aggregate supply curve is called effective demand as at this point all the output produced in the economy is used by the consumers of the economy owing to full employment. 

Effective demand depends on supply price. Effective demand refers to that point where aggrgate demand is equal to aggregate supply. Therefore, supply price and demand price are independent.

In the case of unitary elastic demand, the total outlay of the consumer before the price change and after the price change will remain the same. This is a hypothetical case as there is no real life examples for the same. 

True. Life saving medicines have inelastic demand. By inelastic we mean when the price changes that consumer buying habit remains the same. The consumer will not reduce the consumption of a life saving drug is the price increase and vice versa. 

True.  Government expenditure increases Aggregate demand. Its one of the components to determine demand. Aggregate demand takes into account all the expenditure incurred in the country during the year. Government spending can be in the form of welfare, pension etc which increases the purchasing power of the people thereby increasing demand. 

False. If the demand is less than unitary elastic, the total outlay of the consumers will change in the same direction of change in price. In this case when the total expenditure rises with a rise in price and decreases with a fall in price elasticity will be less than 1.  

A monopolist is able to maximize his profits when his marginal cost is equal to marginal revenue. The profit-maximizing choice for the monopoly will be to produce at the quantity where marginal revenue is equal to marginal cost: that is, MR = MC.

Marginal revenue refers to the change in revenue or additional revenue which a firm earns on selling a unit more of its output. IT is the change in Revenue= Price x Quantity.

$\displaystyle MR =\frac {Change\, in\,TR}{Change \,in\, output}$
$\displaystyle =\frac{(10 \times 19) - (20 \times 9)}{10 - 9} = Rs.\, 10$

An increase in demand causes the equilibrium price to rise. On the other hand, a decrease in demand causes the equilibrium price to fall. An increase in supply causes the equilibrium price to fall, while a decrease in supply causes the equilibrium price to rise

In every market a firm should produce either if they are earning profits or if they are able to cover up total variable cost, i.e. if total revenue is greater than total variable cost.

For profit to be maximized the difference between MR and MC should be zero. If MR > MC it is profitable to increase production and when MR < MC it is profitable to decrease production. And the MC curve should intersect the MR curve from below for maximising profit in absolute terms. (Higher output will lead to larger total revenue).

Equilibrium market price is a point where the demand equals the supply for a particular commodity. Hence, in the given illustration, demand (700) is equal to supply (700) at Rs.4. Hence, it is equilibrium market price.

If demand decreases and supply increases then equilibrium quantity could go up, down, or stay the same, and equilibrium price will go down. If demand decreases and supply decreases then equilibrium quantity goes down, and the equilibrium price could go up, down, or stay the same

A change in the price of the product leads to movement along the demand curve and not a shift in the demand curve.

An increase in demand while the supply remains unchanged causes equilibrium price and quantity to increase. Due to increase in demand the quantity demanded will increase this will thereby increase competition in the market which will leaf to increase in price of the product. hence, when the price increases demand decreases to reach to equilibrium and new equilibrium quantity and price will be derived. 

Producer's equilibrium refers to a situation of profit maximization.
It is only when (a) MR = MC, and (b) MC is rising, these two conditions are satisfied, then a producer will reach the point of his equilibrium and maximizing his profit.

A producer strikes his equilibrium when he produces that amount of output at which the difference between total revenue and total cost is maximum. This is because, $\text{Net profit} = TR - TC$.

A producer strikes his equilibrium only when $MP$ is diminishing, where the $MC$ is simultaneously rising. The producer stops production when rising $MC$ matches with falling $MR$. Beyond this point, rising $MC$ would exceed $MR$, causing loss of profit.