Answer: False
Explanation: The nucleus of an atom only contains the protons and neutrons.
The electrons are not found in the nucleus,
they are orbiting the nucleus in different shells.
It's pretty easy to balance equations! Basically you want to make sure that the number of each compound is equal on both sides of the arrow.
For example number one is
Fe + H2SO4 -> Fe2(SO4)3 + H2
A 3 in front of H2SO4 because there's a subscript of 3 on the right side.
Then a 3 in front of H2 because of the previous step.
Then add a 2 in front of Fe because of the 2 subscript in Fe2(SO4)3
Then add a 1 in front of Fe2(SO4)3 because you already have an equal number of each element.
<u>2</u>Fe + <u>3</u>H2SO4 -> <u>1</u>Fe2(SO4)3 + <u>3</u>H2
I hope this explanation helps! You should really do your homework because practice is everything when it comes to chemistry. You'll need to know how to do it for exams.
Answer : All of the above are valid expressions of the reaction rate.
Explanation :
The given rate of reaction is,

The expression for rate of reaction for the reactant :
![\text{Rate of disappearance of }NH_3=-\frac{1}{4}\times \frac{d[NH_3]}{dt}](https://tex.z-dn.net/?f=%5Ctext%7BRate%20of%20disappearance%20of%20%7DNH_3%3D-%5Cfrac%7B1%7D%7B4%7D%5Ctimes%20%5Cfrac%7Bd%5BNH_3%5D%7D%7Bdt%7D)
![\text{Rate of disappearance of }O_2=-\frac{1}{7}\times \frac{d[O_2]}{dt}](https://tex.z-dn.net/?f=%5Ctext%7BRate%20of%20disappearance%20of%20%7DO_2%3D-%5Cfrac%7B1%7D%7B7%7D%5Ctimes%20%5Cfrac%7Bd%5BO_2%5D%7D%7Bdt%7D)
The expression for rate of reaction for the product :
![\text{Rate of formation of }NO_2=+\frac{1}{4}\times \frac{d[NO_2]}{dt}](https://tex.z-dn.net/?f=%5Ctext%7BRate%20of%20formation%20of%20%7DNO_2%3D%2B%5Cfrac%7B1%7D%7B4%7D%5Ctimes%20%5Cfrac%7Bd%5BNO_2%5D%7D%7Bdt%7D)
![\text{Rate of formation of }H_2O=+\frac{1}{6}\times \frac{d[H_2O]}{dt}](https://tex.z-dn.net/?f=%5Ctext%7BRate%20of%20formation%20of%20%7DH_2O%3D%2B%5Cfrac%7B1%7D%7B6%7D%5Ctimes%20%5Cfrac%7Bd%5BH_2O%5D%7D%7Bdt%7D)
From this we conclude that, all the options are correct.

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.

Answer:
1. 
2. 
Explanation:
An ion is formed when an atom that is said to be neutral gains or losses electrons.
It is thought that a negative ion (anion) is produced as it gains electrons and a positive ion (cation) is formed when it loses an electron.
Atomic number is the total number of protons and electrons in a neutral atom.
From the information
Protons = 14
electron = 18
Net Charge = no of proton - no of electron
= 14 - 18 = -4
Mass number = 14 + 15 = 29
Thus, the chemical symbol = 
For ion with 27 proton, 32 neutrons and 25 electrons
Net charge = 27 - 25 = +2
Mass number = 27 + 32 = 59
Thus, the chemical symbol = 