Endothermic reaction : A reaction in which the system absorb energy, usually in the form of heat
the one that is an endothermic reaction is : D. Thawing ice
hope this helps
Explanation:
Principle Quantum Numbers : It describes the size of the orbital and the energy level. It is represented by n. Where, n = 1,2,3,4....
Azimuthal Quantum Number : It describes the shape of the orbital. It is represented as 'l'. The value of l ranges from 0 to (n-1). For l = 0,1,2,3... the orbitals are s, p, d, f...
s = 1 orbital
p = 3 orbitals
d = 5 orbitals
f = 7 orbitals
For n = 4
l = 0 to (n-1) = 0 to 3 = (4s , 4p , 4d , 4f)
Number of subshells = 4
Number of orbitals = 1 + 3 + 5 + 7 = 16
The maximum number of electrons the n = 4 shell can contain:
Each orbital can holds upto two electrons, then 16 orbitals will have :

32 is the maximum number of electrons the n = 4 shell can contain
<span>In the field of science, usually, the product of an experiment is
computed ahead to understand if it reached a specific objective. It would reach
greater than 100% of percent yield if the factors include faster reaction rates;
proper handling of the reactants, no outside contaminants, and the procedure of
the experiment is followed smoothly. It would reach lesser than 100% percent yield
if the experiment is not followed, external factors such as contamination from
the environment (wind, moisture, etc). </span>