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

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

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

Nitric oxide (NO) is a highly reactive gas with a short atmospheric lifetime.

Its residence time is typically a few hours, due to rapid chemical reactions with other atmospheric compounds.

Explanation

A commutator is used in DC motors and generators to reverse or maintain the direction of current correctly.

It ensures that the current flows in one direction through the external circuit.

Explanation

In electrical-mechanical analogies, mass (which resists acceleration) corresponds to inductance, which resists changes in current.

Just as mass stores mechanical energy, inductance stores magnetic energy.

Explanation

In the resistor color code, orange represents the digit 3.

This value is used in the first two bands (significant figures) or as the multiplier depending on the band position.

Explanation

The power (P) is given by:

P = VI

Given P = 100 W and V = 200 V, we can find the current (I):

100 = 200 × I

I = 100 / 200

= 0.5 A

Explanation

Electric current is defined as the rate of flow of charge through a conductor.

Its formula is 𝐼 = 𝑄/𝑡, where 𝐼 is current, 𝑄 is charge, and 𝑡 is time.

Explanation

The total resistance (R) in the series circuit is:

R = 5 + 10 + 10

= 25 Ω

The current (I) is given by Ohm's law:

I = V/R

= 50V / 25Ω

= 2A