Answer: 
is a reactant; it is present before the reaction occurs.
Explanation:
In a chemical reaction the chemical formulas written before the arrow are described as reactants as they react together to form products which are written after the arrow.
Thus and HCl are reactants here whereas 
, 
and 
are products.
The best option i think is b would be my best answer
a=electronic equipment and jewelry
Answer:
Because time is independent of distance, and distance is dependent of time.
Explanation:
Usually, on any graph, the independent variable is plotted on the x-axis and the dependent variable is plotted on the y-axis. Because of this, time, which is independent (time happens regardless of any other factor), is on the x-axis while distance, which is the dependent variable (can only take place in time), is on the y-axis.
