Answer:
c. CH4 < NH3 because the NH bond is more polar than the CH bond.
Explanation:
Actually, the electronegativity difference between carbon and hydrogen is just about 0.4. This meager difference in electronegativity corresponds to a nonpolar bond between the two atoms.
However, the electronegativity difference between nitrogen and hydrogen is about 0.9. This larger electronegativity difference corresponds to the existence of a polar covalent bond between the two atoms.
Hence the N-H bond is significantly polar unlike the C-H bond. This implies that CH4 molecules are only held together by weak dispersion forces while NH3 molecules are held together by stronger dipole-dipole interactions and hydrogen bonds.
Method means a particular form or procedure for accomplishment or approaching something, especially a systematic or established one.
The chemical formula for the compound strontium sulphide would be SrS.
Answer:
The electron from the ground state to occupy a next energy level. In this case,we say that the electron is excited
The atomic mass is defined as the mass an atom of an element. The atomic mass in approximation is equal to the sum of number of neutrons and protons in the nucleus of an atom (mass number). The units which are used for measuring the atomic mass is atomic mass unit, 
.
Thus, the correct option is option E that is atomic mass unit is used for measuring atomic mass.
