A convex lens is called a convergent lens because it converges (brings together) parallel rays of light that pass through it.

When ethylene (C₂H₄) reacts with bromine (Br₂), an addition reaction occurs. The double bond in ethylene breaks and bromine atoms add across the carbon atoms, forming 1,2-dibromoethane.

Balanced Chemical Equation:

C₂​H₄ ​+ Br₂​ → C_2​H_4​Br₂

Resistance is derived from Ohm's Law:

R = V/I

This means resistance (R) is the ratio of voltage (V) to current (I). It shows how much a material opposes the flow of electric current.

c. CH₄ (Methane)

Explanation: Greenhouse gases like methane (CH₄) absorb long-wavelength infrared radiation emitted by the Earth's surface, trapping heat in the atmosphere.

a. 4.4 g CO₂

Explanation: 

4.4 g CO₂:

Molar mass of CO₂ = 44 g/mol

Moles of CO₂ = 4.4 / 44 = 0.1 mol

Volume = 0.1 × 22.4  = 2.24 L

a. 6.022 × 10²³

c. 3

Explanation: For a solid, there are three types of thermal expansion coefficients:

• Linear expansion coefficient
• Area expansion coefficient
• Volumetric expansion coefficient

c. Infrared ray

b. 15°

Explanation:

The angle of deviation (δ) in refraction is given by the formula:

δ = Angle of incidence − Angle of refraction

Here, the angle of incidence is 45° and the angle of refraction is 30°. So,

δ = 45 ° − 30 ° = 15°

a. V ∝ I

Explanation: Ohm's Law states that the current (I) flowing through a conductor between two points is directly proportional to the potential difference (V)

V = IR

d. Q = W/V

b. Atomic number increases

Explanation: During β-particle emission (β-decay), a neutron in the nucleus of a radioactive atom is converted into a proton, emitting a β-particle (an electron) and an antineutrino. This process increases the atomic number of the atom by 1.