The gas used in refrigerators is MCQ with Answer and Explanation

Explanation:
Myopia (nearsightedness): image formed before retina, corrected with concave lens. Hypermetropia: cannot see near objects. Presbyopia age-related. Cataract lens opacity.

Explanation:
The acceleration due to gravity is given by g = GM/R². For a small change, taking the derivative or using error approximation: Δg/g = -2(ΔR/R). If R shrinks by 1% (ΔR/R = -1%), then Δg/g = -2(-1%) = +2%. Therefore, the value of 'g' will increase by approximately 2%.

Explanation:
v_esc ∝ √(M/R). New ∝ √(4M/2R) = √(2M/R) = √2 √(M/R) = √2 v.