The theory of the firm under perfect competition — Economics STD 11 Commerce — Question

Giving reasons, state whether the following statements are true or false.
When there are diminishing returns to a factor, total product first increases and then starts falling.

Giving reasons, state whether the following statement are true or false:
When there are diminishing returns to a factor, marginal product and total product both always fall or diminish.

Giving reasons, state whether the following statements are true or false.
If price of substitute goods falls, demand for related goods will also fall?

MP = AP when AP is maximum.

Giving reasons, state whether the following statements are true or false.
Under monopoly new firms can enter the industry to raise the supply.

Should the difference between ATC and AVC be constant, because TFC is constant?

Variable cost is incurred before production is started.

In response to constant and positive marginal revenue, both total revenue and average revenue tend to rise at a constant rate.

The demand for a commodity always increases with increase in the prices of other goods. True or false?