<u>Answer:</u> The quantity of every prefix is written below as a power of ten.
<u>Explanation:</u>
In the metric system of measurement, the name of multiples and subdivision of any unit is done by combining the name of the unit with the prefixes.
<u>For Example:</u> deka, hecto and kilo means 10, 100 and 1000 respectively. Deci, centi and milli means one-tenth, one-hundredth, and one-thousandth respectively.
The quantity of these prefixes are written as the power of 10.
For the given prefixes:
<u>Nano:</u> The quantity will be 
<u>Kilo:</u> The quantity will be 
<u>Centi:</u> The quantity will be 
<u>Micro:</u> The quantity will be 
<u>Milli:</u> The quantity will be 
<u>Mega:</u> The quantity will be 
Hence, the quantity of every prefix is written above as a power of ten.
Answer:
d. 0.208 M NaOH
Explanation:
M[NaOH] = 23+16+1= 40g/mol
2.40L = 2.4dm3
M=m/Mv
M=20.0g/40g/mol×2.4dm3
M=20.0g ÷ 96
M= 0.208 M NaOH

As long as the equation in question can be expressed as the sum of the three equations with known enthalpy change, its
can be determined with the Hess's Law. The key is to find the appropriate coefficient for each of the given equations.
Let the three equations with
given be denoted as (1), (2), (3), and the last equation (4). Let
,
, and
be letters such that
. This relationship shall hold for all chemicals involved.
There are three unknowns; it would thus take at least three equations to find their values. Species present on both sides of the equation would cancel out. Thus, let coefficients on the reactant side be positive and those on the product side be negative, such that duplicates would cancel out arithmetically. For instance,
shall resemble the number of
left on the product side when the second equation is directly added to the third. Similarly
Thus
and

Verify this conclusion against a fourth species involved-
for instance. Nitrogen isn't present in the net equation. The sum of its coefficient shall, therefore, be zero.

Apply the Hess's Law based on the coefficients to find the enthalpy change of the last equation.

A;4, b;6, c;7, d;5, e;8, f;3