The answer is the el second one since it is a physical change
Table salt is sodium chloride mixed with small<span> amount of </span>potassium iodide (KI)<span>, </span>sodium iodide (NaI)<span> or </span>sodium iodate (NaIO₃)<span>.
Atomic level - sodium chloride (NaCl) has crystal cubic structure (</span>lattice-type arrangement)<span> with ionic bonds. Sodium is cation with charge 1+ and chlorine is an anion with charge 1-.
Macroscopic level - table salt is c</span>olorless crystal, soluble in water with high melting and boiling temperature..
Answer : The correct option is, (A) -x kJ/mol
Explanation :
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
The given chemical reaction is,

Now we have to determine the value of
for the following reaction i.e,

According to the Hess’s law, if we reverse the reaction then the sign of
change.
So, the value
for the reaction will be:


Hence, the value of
for the reaction is -x kJ/mole.
c cell wall human cells do not have cell walls but do have cell membranes unlike plants that have both
Answer: (D) environmental chemistry
Explanation: