<span>Mantle convection is the slow creeping motion of Earth's rocky mantle caused by convection currents carrying heat from the interior of the earth to the surface. It is one of 3 driving forces that causes tectonic plates to move around the Earth's surface.</span>
Explanation;
Writing scientific notation :
- Move the decimal to the left side until single digit of number remains before the decimal.
- Then we will count the number of times we moved the decimal. Write this number as the exponential power of number '10'.
- For Example:

Radius of the sun = 696,000.0 kilometer

Radius of the sun can also be written as =
Size of bacterial cell =
millimeter

Size of bacterial cell can also be written as = 
Answer:
Option-D (Piece of Wood) is the correct answer.
Explanation:
Density is related to mass and volume as,
Density = Mass / Volume
For Wood,
Density = 42.5 / 50
Density = 0.85
You can calculate remaining densities by yourself. Among all the density of Piece of Wood is the least.
Answer:
Equilibrium constant for the reaction at 25⁰C = 1.81 x 10⁻⁶
Explanation:
Reaction for the Haber's process
N₂(g) + 3 H₂(g) ⇌ 2 NH₃(g)
Free energy change of reaction
ΔGr° = ∑products free energy - ∑reactants free energy
= 2 x (- 16.4) - 0
= - 32.8 KJ / mole
Equilibrium constant for this reaction at 25⁰C
ΔGr° = - 2.303 RT log K
⇒ log K = 
⇒ K = Anti log( -5.74) = 1.81 x 10⁻⁶