At what temperature does gallium become a liquid?

• 0°C

• 30°C

• 100°C

• 50°C

Answer explanation

Gallium melts at approximately 29.76°C, which is rounded to 30°C. Therefore, gallium becomes a liquid at 30°C, making it the correct choice among the options provided.

What state is gallium at room temperature?

• Gas

• Liquid

• Solid

• Plasma

Answer explanation

Gallium is a metal that is solid at room temperature, with a melting point of about 29.76 °C. Therefore, at typical room temperatures, gallium exists in a solid state.

What happens to gallium when it is melted?

• It evaporates

• It forms crystals

• It becomes a gas

• It turns into ice

Answer explanation

When gallium is melted, it does not evaporate or turn into gas; instead, it can form crystals as it cools down. This is a characteristic behavior of gallium, making 'It forms crystals' the correct answer.

In which industries is gallium commonly used?

• Textile and fashion

• Semiconductors and LEDs

• Food and beverage

• Automotive

Answer explanation

Gallium is primarily used in the semiconductor industry for making integrated circuits and in LEDs for lighting and displays, making 'Semiconductors and LEDs' the correct choice.

What effect does gallium have on aluminum?

• It strengthens it

• It eats away at it

• It makes it shiny

• It turns it into gold

Answer explanation

Gallium has a detrimental effect on aluminum; it diffuses into the aluminum and causes it to become brittle and weak, effectively 'eating away' at it. This makes the correct answer 'It eats away at it'.

What is the first step in the procedure for the lab experiment?

• Fill the beaker with crushed ice.

• Record the temperature of the ice.

• Read and complete a lab safety form.

• Turn on the hot plate to medium-high.

Answer explanation

The first step in any lab experiment is to ensure safety. Reading and completing a lab safety form helps identify potential hazards and necessary precautions, making it the correct initial action before proceeding with the experiment.

What should you use to hold a beaker while stirring ice in a lab?

• A spoon

• A hot mitt

• A thermometer

• A measuring cup

Answer explanation

A hot mitt is the correct choice to hold the beaker while stirring ice, as it protects your hands from the cold temperature. A spoon, thermometer, or measuring cup do not provide the necessary insulation.

What happens to the temperature of a substance during a phase change from solid to liquid?

• It increases steadily.

• It decreases steadily.

• It remains constant.

• It fluctuates randomly.

Answer explanation

During a phase change from solid to liquid, the temperature of the substance remains constant. This is because the energy added is used to break intermolecular bonds rather than increase temperature.

What is the term used to describe the point at which a substance changes from a solid to a liquid?

• Boiling point

• Freezing point

• Melting point

• Condensation point

Answer explanation

The term 'melting point' refers to the temperature at which a solid turns into a liquid. It is distinct from the boiling point, which is when a liquid becomes a gas, and the freezing point, which is when a liquid turns into a solid.

What is the change of state from a gas to a liquid called?

• Evaporation

• Condensation

• Boiling

• Freezing

Answer explanation

The change of state from a gas to a liquid is called condensation. This process occurs when gas molecules lose energy and come together to form a liquid, contrasting with evaporation, which is the transition from liquid to gas.