Final answer:
The statement is false; indifference curves for perfect substitutes are straight lines with a constant slope, representing a constant rate of substitution between the goods.
Step-by-step explanation:
The statement that indifference curves for perfect substitutes are right angles is false. Indifference curves for perfect substitutes are not right-angled but are instead straight lines with a constant slope. This is because perfect substitutes can be exchanged for one another at a constant rate. For example, if tea and coffee are perfect substitutes, a consumer would be willing to substitute one for the other at the same rate, regardless of how much they consume, and their indifference curve would be a straight line. Indifference curves for most goods are downward sloping and convex to the origin. They are steeper on the left and flatter on the right due to diminishing marginal utility. As a person consumes more of one good, the amount of the other good they require to maintain the same level of utility decreases. The curve's slope is known as the marginal rate of substitution, indicating the rate at which a consumer can give up some amount of one good in exchange for another while maintaining the same level of utility.