Explanation

Methane (CH₄) is a stable greenhouse gas with a relatively long atmospheric lifetime.

Its mean residence time in the atmosphere is approximately 3 to 7 years before it reacts or breaks down.

Explanation

Rectangular components of a vector are its projections along perpendicular axes (typically x and y).

Therefore, the angle between them is always 90 degrees, i.e., they are mutually perpendicular.

Explanation

Cl-CH₂-COOH (chloroacetic acid) is the strongest because the electronegative chlorine atom withdraws electrons, increasing acidity.

This stabilizes the conjugate base, making it a stronger acid than formic acid (HCOOH) or acetic acid (CH₃COOH).

Explanation

NO₂ is a reddish-brown gas that gives photochemical smog its characteristic brownish color.

It is formed by the reaction of NO with oxygen in sunlight.

It is a major pollutant in urban smog.

Explanation

Raney nickel is prepared by treating a nickel-aluminum (Ni-Al) alloy with concentrated NaOH.

This process removes aluminum, leaving behind porous nickel, which acts as an excellent hydrogenation catalyst.

Explanation

Water (H₂O) is composed of 2 hydrogen atoms (1g each) and 1 oxygen atom (16g) → total molar mass = 18g.

Percentage of oxygen = (16/18) × 100 = 88.8% by mass.

Explanation

Silicon is the most widely used material in semiconductor devices due to its:

• Abundance in nature

• Suitable electrical properties

• Excellent thermal stability

• Formation of a stable oxide layer (SiO₂), which is useful in device fabrication

While germanium was used in early semiconductors and gallium nitride is used in high-power or high-frequency applications, silicon remains the industry standard.

Explanation

Yellow cytoplasm in Ascidian cells gives rise to muscle cells. 

In ascidians, a type of marine invertebrate, the yellow cytoplasm is a distinct region of the fertilized egg that contains specific molecules responsible for muscle development.

Cells that inherit this yellow cytoplasm during cell division will differentiate into muscle cells.

This is why the correct answer is c. Muscle cell. 

Explanation

 A dilute solution compared to cell concentration is termed hypotonic

This means the solution has a lower concentration of solutes (and a higher concentration of water) than the cell's internal environment. 

Explanation

The reaction where larger hydrocarbons (like C₈H₁₈) break into smaller ones (like C₃H₆ and fragments) is called cracking.

Cracking is commonly used in the petroleum industry to produce smaller, more useful hydrocarbons such as alkenes and gasoline.