Answer:
(b). Mass and distance.
Explanation:
The gravitational force between two objects is given by Newton's law of universal gravitation. The formula is as follows :

Here,
G is universal gravitational constant
r is the distance between two objects
It is very clear that the gravitational force is directly proportional to the product of masses and inversely proportional to the square of the distance between them.
Hence, the two quantities are used to predict gravitational force according to Newton's law of universal gravitation are mass and distance.
Answer : The equilibrium concentration of
at
is,
.
Solution : Given,
Equilibrium constant, 
Initial concentration of
= 0.260 m
Let, the 'x' mol/L of
are formed and at same time 'x' mol/L of
are also formed.
The equilibrium reaction is,

Initially 0.260 m 0 0
At equilibrium (0.260 - x) x x
The expression for equilibrium constant for a given reaction is,
![K_c=\frac{[H_3O^+][C_2H_3O_2^-]}{[HC_2H_3O_2]}](https://tex.z-dn.net/?f=K_c%3D%5Cfrac%7B%5BH_3O%5E%2B%5D%5BC_2H_3O_2%5E-%5D%7D%7B%5BHC_2H_3O_2%5D%7D)
Now put all the given values in this expression, we get

By rearranging the terms, we get the value of 'x'.

Therefore, the equilibrium concentration of
at
is,
.
I think number one is c not sure or not number 2 is C AND NUMBER 3 IS 1 Go with sliding friction number 2 go with rolling friction number 3 is static friction and 4 is force
Answer:
I think C if not then B
Explanation:
Heat will change the product and will become a chemical change.