Explanation

In methane (CH₄), the carbon atom forms four sigma bonds with hydrogen atoms.

To form these four equivalent bonds, carbon undergoes sp³ hybridization, resulting in a tetrahedral structure.

Explanation

Chlorofluorocarbons (CFCs) release chlorine atoms in the stratosphere, which break down ozone (O₃) molecules.

This reaction is the main cause of ozone layer depletion.

Explanation

The coordination number of a metal atom in a complex is the number of ligands directly attached to it.

In [PtCl(NO)(NH₃)₂], the ligands are:

• Cl⁻ (1)
• NO (1)
• NH₃ (2)

Total number of ligands = 1 + 1 + 2 = 4

The coordination number of Pt is 4, since it is bonded to 4 ligands.

Explanation

STH (Somatotropic Hormone) is also known as Growth Hormone (GH).

It promotes protein synthesis even after the growth phase ends.

It plays a role in tissue maintenance, muscle development, and metabolism throughout life.

Explanation

The phrase "When I met him" is in the past tense, so we need a past continuous verb to show an action in progress at that time.

"Was going" correctly shows he was in the process of going to college when the meeting happened.

Explanation

Elements of Group IVA (Group 14) like carbon (C) and silicon (Si) have very high melting points due to strong covalent bonding.

For example, diamond (carbon) has the highest melting point among all elements.

Explanation

The fine ruling (track spacing) on a CD is about 0.5 micrometers (µm).

This microscopic spacing allows the CD to store large amounts of data through optical encoding.

Explanation

Endocrine glands secrete hormones directly into the bloodstream, without using ducts.

Examples include the pituitary, thyroid, adrenal, and pancreas (as an endocrine gland).

Explanation

Group VB (Group 7 in modern IUPAC numbering) of transition elements includes Manganese (Mn), Technetium (Tc), and Rhenium (Re).

These elements show similar properties and lie vertically in the same group of the periodic table.

Explanation

Acetic acid is used to produce cellulose acetate, a key component in making synthetic fibers like rayon.

It acts as a solvent and reactant in the fiber manufacturing process.