Answer:
Option A
Explanation:
Leguminous plants like pulses etc. have root nodules comprising of rhizobacterium which live in a symbiotic relationship with the roots of the plant and in turn fix the nitrogen in the soil in the roots of the leguminous plants.
Hence, option A is correct
<u>Answer:</u> The correct answer is the mass number of the most common isotope of the element is 24.
<u>Explanation:</u>
We are given:
An element having atomic number 12 is magnesium and atomic mass of the element is 24.305
The image corresponding will be 
The number '24.305' is the average atomic mass of magnesium element.
Average atomic mass is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.
Formula used to calculate average atomic mass follows:

Average atomic mass of magnesium = 24.305 amu
As, the average atomic mass of magnesium lies closer to the mass of Mg-24 isotope. This means that the relative abundance of this isotope is the highest of all the other isotopes.
The 'Mg-24' isotope is the most common isotope of the given element.
Hence, the correct answer is the mass number of the most common isotope of the element is 24.
2 hydrogen and 1 oxygen makes water
Answer:

Explanation:
The molar mass is the mass of a substance in grams per mole.
To find it, add the mass of each element in the compound. These masses can be found on the Periodic Table.
The compound given is:

The compound has 1 Ca (calcium) and 2 Cl (chlorine).
Mass of Calcium
- The molar mass of calcium is 40.08 g/mol
- There is only one atom of Calcium in CaCl₂, so the number above is what we will use.
Mass of Chlorine
- The molar mass of chlorine is 35.45 g/mol
- There are two atoms of chlorine in CaCl₂, therefore we need to multiply the molar mass by 2.
- 35.45 * 2= 70.9 g/mol
Molar Mass of CaCl₂
- Now, to find the molar mass, add the molar mass of 1 calcium and 2 chlorine.
- 40.08 g/mol + 70.9 g/mol =110.98 g/mol
The molar mass of CaCl₂ is <u>110.98 grams per mole. </u>
Answer:
I think option (d) is right answer