Answer: The nuclide symbol of X is 
Explanation:
The given nuclear reaction is a type of alpha decay process. In this process, the nucleus decays by releasing an alpha particle. The mass number of the nucleus is reduced by 4 units and atomic number is also decreased by 2 units. The particle released is a helium nucleus.
The general equation representing alpha decay process is:

For the given equation :

As the atomic number and mass number must be equal on both sides of the nuclear equation:

Thus the nuclide symbol of X is 
Answer: Na, S, Cl
Explanation:
Atomic size decreases as one moves from left to right on the periodic table with elements in the same period. This is as a result of the electrons increasing in the outer circle and thus being drawn to the protons in the nucleus which will lead to the outer shell area decreasing.
Sodium (Na) comes before Sulfur (S) which comes before Chlorine (S) so this is the decreasing order as they are all in the same period.
Your answer would be boiling water because it creates stem and stem is pressure i hope this helps
Answer:
Benzaldehyde is less electrophilic than acetaldehyde
Explanation:
Electrophilicity of carbonyl carbon depends on it's positive charge density.
In benzaldehyde, phenyl group can act as an electron donating group towards carbonyl group due to it's electron donating resonating effect.
In acetaldehyde, methyl group can act as an electron donating group towards carbonyl group due to it's electron donating inductive effect.
We know that resonating effect are more stronger than inductive effect.
Henece, it is expected that positive charge density on carbonyl carbon is much lower in benzaldehyde than acetaldehyde.
So, benzaldehyde is less electrophilic than acetaldehyde.
Resonating effect of phenyl group has been shown below.
The magnitude of the force required to change the length of a spring-like object is directly proportional to the spring constant and the displacement of the spring. Elastic potential energy is directly proportional to the square of the change in length and the spring constant.