A vulcanized flexible tyre rubber contains about 3 –5% of sulphur whereas hard rubber (ebonite) contains about 32% of sulphur. The stiffness of vulcanized rubber depends on the amount of sulphur added.

Correct Option: B

A vulcanized flexible tyre rubber contains about 3 –5% of sulphur whereas hard rubber (ebonite) contains about 32% of sulphur. The stiffness of vulcanized rubber depends on the amount of sulphur added.

The atomic radius is the distance from the atomic nucleus to the outermost stable electron orbital in an atom that is at equilibrium. It tends to decrease across a period from left to right. It usually increases while going down a group due to the addition of a new energy level (shell).

Correct Option: A

The atomic radius is the distance from the atomic nucleus to the outermost stable electron orbital in an atom that is at equilibrium. It tends to decrease across a period from left to right. It usually increases while going down a group due to the addition of a new energy level (shell).

Sodium is a very reactive metal. It reacts vigorously with oxygen and water. A lot of heat is generated in this process. Therefore, it is stored in kerosene to avoid contacts between either atmospheric oxygen or water.

Correct Option: A

Sodium is a very reactive metal. It reacts vigorously with oxygen and water. A lot of heat is generated in this process. Therefore, it is stored in kerosene to avoid contacts between either atmospheric oxygen or water.

The noble gases are the chemical elements in group 18 of the periodic table. This chemical series contains helium, neon, argon, krypton, xenon, and radon.

Correct Option: A

The noble gases are the chemical elements in group 18 of the periodic table. This chemical series contains helium, neon, argon, krypton, xenon, and radon.

Vulcanization is a chemical process for converting natural rubber into more durable materials via the addition of sulfur or other equivalent curatives or accelerators. These additives modify the polymer by forming cross-links (bridges) between individual polymer chains.

Correct Option: A

Vulcanization is a chemical process for converting natural rubber into more durable materials via the addition of sulfur or other equivalent curatives or accelerators. These additives modify the polymer by forming cross-links (bridges) between individual polymer chains.