QA of wrong answered questions

• Mercury is the only Liquid Metal of room temperature and pressure.
• Which of the following substances must not be a metal at room temperature and pressure?

  1. A brown solid
  2. A silvery liquid
  3. A golden yellow solid
  4. A golden yellow gas

  4 ( must not be metal = gas )
• Which of the following statement about non-metals is correct?

  1. All non-metals have low melting point.
  2. All non-metals are brittle.
  3. Silicon is a non-metal.
  4. Non-metal may conduct electricity.

  4 ( graphite which is a non-metal have high melting point not brittle and could conduct electricity. While silicon is not a non-metal. )
• Element P is a solid which conducts electricity at room temperature. Which of the following statements are INCORRECT?

  (1) element P must be a metal

  (2) element P must not be a non-metal

  (3) element P is dull in colour

  1. (1)(2)
  2. (1)(3)
  3. (2)(3)
  4. (1)(2)(3)

  4 ( metals, graphite which is a non-metal, and semi-metals when they are heated or slightly impure could conduct electricity )
• iodine is classified as a non-metal because

  1. It has a low melting point
  2. it is a poor conductor of electricity
  3. it dissolves slightly in water
  4. it can sublime

  2 (non-metal = poor conductor of electricity)
• Silicon is commonly used in making micro-computer chips.