Answer:
Option A (0.043 g) is the correct answer.
Explanation:
Given:
= 43 mg
As we know,

then,
⇒ 
Thus, the above is the correct alternative.
Answer:
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Number of molecules NH₃ = 4.45 x 10²²
<h3>Further explanation
</h3>
A mole is a number of particles(atoms, molecules, ions) in a substance
This refers to the atomic total of the 12 gr C-12 which is equal to 6.02.10²³, so 1 mole = 6.02.10²³ particles
Can be formulated :
N = n x No
N = number of particles
n = mol
No = 6.02.10²³ = Avogadro's number
mol of NH₃ = n = 0.074
So the number of molecules :

Explanation:
Different heating process affect the microstructure of the steel in different ways. Thus, imparting different properties to the steel. For example, annealing is done is done to impart softness to steel, hardening is done to hardened the steel( eg: carburizing, nitriding, cyaniding) whereas tempering is done to improve the ductility of the steel.
Steel mainly contains iron and carbon. This percentage of carbon and iron decides the property of the steel. It is the % of carbon which is altered in different heating process that to obtained the desire microstructure in steel.
The three group 4 elements that occur naturally are titanium, zirconium, and hafnium. The first three members of the group share similar properties; all three are hard refractory metals under standard conditions.