Explanation

Explanation

• Phenolphthalein is a pH indicator that changes color in response to changes in acidity or basicity.
• In an acidic medium, it is colorless, and in a basic medium, it turns pink.

Explanation

Explanation

Polio is also known as poliomyelitis.

It is a disease caused by the poliovirus.

The virus is usually spread through the fecal-oral route, which includes through contaminated water and food.

Explanation

A catalyst is a substance that speeds up a chemical reaction without being consumed or altered.

Catalysts increase the rate of reaction by lowering the activation energy required for the reaction to occur.

Explanation

Since fluorine is more electronegative, its oxidation state is -1.

The molecule OF2 has zero overall charge:

O + 2F = 0

x + 2(-1) = 0

x - 2 = 0

x = +2

Explanation

Period Length in Periodic Table:

Period 6 has 32 elements (including lanthanides), making it the longest.

Period 7 is incomplete but will match Period 6 when fully discovered.

Explanation

Graphite is used in nuclear reactors as a neutron moderator.

It slows down high-energy neutrons to thermal energies to maintain the chain reaction efficiently.

Explanation

Rusting of iron is a chemical reaction where iron reacts with oxygen and water to form iron oxide (rust).

Unlike physical changes like melting or bending, rusting involves a chemical transformation.

Explanation