If there is no net force on an object, then the object will <span>maintain it's rate of speed. Basically, net force is the change in an object's motion. If it is stationary and not moving, the object will stay stationary. If the object is moving at a rate of 2 miles per hour, it will constantly continue to move 2 mph because there is no net force.</span>

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.

Explanation:
Atomic radius decreases from left to right in a period.
Therefore Calcium would have a smaller atomic size.
Answer:
5.85 x 10⁻² mol Au
Explanation:
Divide the atoms of gold with Avogadro's number to find the solution.
Answer:
9 days, or 3 half-lives
Explanation:
5.2x10^5=520000
6.5x10^4=65000
65000/520000=1/8, or 3 half-lives
3x3=9 days
I'm not the greatest at Chem but this seems more like math than Chem :)