It's simple.
the number of protons in an atom never changes. And also, the no of protons is its atomic number.if you look up the periodic table, you will find a number on the top - left corner of each of the boxes. This is the atomic number.No 2 same elements on the periodic table have the same atomic number. So, all you have to do is search for a box that has the number 13 on it.
and by the way ... the element which you're searching for is Aluminium
Answer:
The value for the equilibrium constant for the reaction
at 298K .
What would be the value for the equilibrium constant for the following reaction at the same temperature?

Explanation:
The Kc value for the reverse reaction of the first reaction that is:


For the reverse reaction,


So, it is the inverse of the first Kc value.
Hence, the new Kc value is:

Answer is :
Kc=2.5*10^-25.
Because potassium is more reactive than hydrogen
The given question is incomplete. The complete question is as follows.
A 10 kg iron ball is dropped onto a pavement from a height of 100 m. If half of the heat generated goes into warming the ball,find the temperature increase of the ball. (In Sl units, the specific heat capacity of iron is 450 J/kg.C degree).
Explanation:
In the given case, when the ball comes in contact with the pavement then its kinetic energy will be equal to potential energy of the ball before it was dropped. Half the K.E heats the ball.
As K.E = P.E = mgh
So, mgh =
= 10,000 joules
And, half of this is 5,000 joules
As we know that
Q =
5000 =
= 1.11 degrees
Also, in the given situation
Since there is an m on both sides of the equation, we will divide both sides by m and the resulting equation will be as follows.
As, the result is independent of mass which is why the result is the same for any ball of any mass.