If you only want to balance nuclear reactions, then you should know that number of nucleons are conserved before and after nuclear reaction. Also, charge is conserved as well.
Other things which are conserved in a nuclear reaction are:
Conservation of:
1. Parity
2. Spin
3. angular momentum(vector sum of intrinsic spin and orbital angular momentum)
4. linear momentum
5. Isotopic spin
6. Energy
I think is 1 and a half km
Answer:
186 Liters at STP conditions
Explanation:
1 mole of any gas at STP conditions occupies 22.4 Liters.
Therefore, 8.32 moles O₂(g) = 8.32 moles x 22.4Liters/mole = 186 Liters (3 sig.figs.)
After 3 half-lives, 125 grams of the parent isotope will remain.
Explanation:
The given precipitation reaction will be as follows.

Here, AgCl is the precipitate which is formed.
It is known that molarity is the number of moles present in a liter of solution.
Mathematically, Molarity = 
It is given that volume is 1.14 L and molarity is 0.269 M. Therefore, calculate number of moles as follows.
Molarity = 
0.269 M = 
no. of moles = 0.306 mol
As molar mass of AgCl is 143.32 g/mol. Also, relation between number of moles and mass is as follows.
No. of moles = 
0.307 mol = 
mass = 43.99 g
Thus, we can conclude that mass of precipitate produced is 43.99 g.