Which of the following types of human teeth is used for biting food?

Here are the solutions to the questions:

21. The chemical component of milk of magnesia is

• B. magnesium hydroxide.
  • Milk of magnesia is a common antacid and laxative, with magnesium hydroxide ($Mg(OH)_2$) as its active ingredient.

22. The best method of preventing teenage pregnancy is to

• C. avoid having sex.
  • Abstinence (avoiding sex) is the only method that is 100% effective in preventing pregnancy.

23. An example of an inclined plane is a

• B. path of a hill.
  • An inclined plane is a simple machine that consists of a flat surface tilted at an angle, such as a ramp or a path up a hill.

24. An example of a simple lever which has its effort at the centre is

• B. a pair of forceps.
  • In a Class 3 lever, the effort is applied between the fulcrum and the load. Forceps are an example of a Class 3 lever.

25. Which of the following types of human teeth is used for biting food?

• D. Incisors.
  • Incisors are the sharp, chisel-shaped front teeth used for cutting and biting food.

26. Green plants have the ability to make their own food hence they are known as

• C. producers.
  • Organisms that produce their own food, typically through photosynthesis, are called producers or autotrophs.

27. The ways of conserving electrical energy include
I. putting off electrical appliances when not in use
II. ironing clothes one at a time
III. ironing clothes in bulk

• A. I and III only
  • Turning off appliances when not in use (I) and ironing clothes in bulk (III) are energy-saving practices. Ironing one at a time (II) is inefficient as it requires the iron to heat up repeatedly or stay on for longer for small tasks.

28. The linear sequence of feeding relationship among living things is called

• C. food chain.
  • A food chain describes a single, linear pathway of how energy and nutrients are transferred from one organism to another through feeding.

29. Which of the following planets are closer to the sun than the earth?

• C. Mercury and Venus.
  • The order of planets from the Sun is Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. Therefore, Mercury and Venus are closer to the Sun than Earth.