Reactivity of Alkali Metals with Water

The video tutorial discusses the six alkali metals: lithium, sodium, potassium, rubidium, cesium, and francium. It highlights their soft nature and reactivity, particularly how they react with air and water. The metals quickly corrode in air, with reactivity increasing down the group. In water, they release hydrogen gas, with reactions becoming more vigorous from lithium to cesium. Safety precautions are necessary for handling these reactions.

Which of the following is NOT an alkali metal?

• Lithium

• Calcium

• Potassium

• Sodium

What happens to alkali metals when they are exposed to air?

• They quickly become coated with compounds.

• They dissolve in air.

• They emit a bright light.

• They remain shiny and metallic.

Why is sodium stored under oil?

• To enhance its reactivity.

• To prevent it from reacting with air.

• To keep it shiny.

• To make it easier to cut.

Which alkali metal reacts so quickly with air that its metallic luster is hard to see?

• Lithium

• Sodium

• Potassium

• Cesium

What gas is produced when alkali metals react with water?

• Carbon dioxide

• Hydrogen

• Nitrogen

• Oxygen

What happens when lithium reacts with water?

• It sinks and reacts slowly.

• It floats and reacts, releasing hydrogen gas.

• It dissolves without any reaction.

• It catches fire immediately.

How does the reaction of sodium with water differ from that of lithium?

• It does not produce any gas.

• It is less vigorous.

• It produces a different gas.

• It is more vigorous.

What is observed when potassium reacts with water?

• It floats and the hydrogen gas catches fire.

• It floats and reacts without any visible change.

• It sinks and reacts slowly.

• It dissolves without any reaction.

Why is a safety screen used when reacting rubidium with water?

• To enhance the reaction.

• To observe the reaction more clearly.

• To protect from the intense reaction.

• To prevent the metal from floating away.