Answer:
2.__ Dissolving two solids in water before mixing them together.
4.__ Grinding a solid into fine particles.
5.__ Adding an enzyme catalyst.
Explanation:
The rate of reaction is the measure of the speed of a chemical reaction.
Some factors affects the rate of reactions such as pressure, temperature, concentration, surface area, presence of catalyst.
- Reactions in liquid medium are much faster than those between solids because there is a flow of substances. As they come in contact with one another, collision begins to take place.
- Grinding a solid into fine particles increases the surface area. An increase in surface area increases the rate of reaction.
- Adding an enzyme catalyst lowers the activation energy and reduces the energy barrier that must be overcome before a reaction takes place.
Answer: 
Explanation:
The unbalanced equation is
Balancing this equation, we get:
Correct Answer: option <span>(1) Mn(s)
Reason:
The </span><span>spontaneity of electrochemical cell, depends on the it's Eo value. Electrochemical cells with positve Eo are spontanous and vice-versa.
</span>
In present case, the Eo of half-cell of interest are as follows:
Eo Zn2+/Zn = <span>-0.763v
</span>Eo Mg2+/Mg = 2.37v
Eo Mn2+/Mn = -1.18v
Therefore, Eo cell (with Zn as one of the half-cell) = Eo Zn2+/Zn - Eo Mn2+/Mn
= -0.763 - (-1.18)
= 0.417v
On other hand, Eo cell (with Mg as one of the half-cell) = Eo Mg2+/Zn - Eo Mn2+/Mn
= -2.37 - (-1.18)
= -1.19v
Thus, Mn(s) <span>metal will spontaneously react with Zn2+(aq), but will not spontaneously react with Mg2+(aq)</span>
The number of significant figures within a number are the amount digits that are required to specify a number to a certain degree of accuracy. In the number, 0.0645 g, the 6 is the most significant figure and 4 is the second most significant figure. Therefore, rounding to two significant figures yields 0.064g.
