Answer:
13. A
14. C
Explanation: i tried my best
You have to switch the elements based in if they're metals/nonmetals. so nonmetals switch with each other and metals switch with each other.
AB + CD ---> AC + BD
Answer:
The balanced molecular equation for the reaction :

Explanation:
The reaction between copper(II) nitrate and potassium carbonate gives solid precipitate of copper(II) carbonate and aqueous solution of potassium nitrate.

According to reaction, 1 mole of copper(II) nitrate reacts with 1 mole of potassium carbonate to give 1 mole of copper(II) carbonate and 2 moles of potassium nitrate,
Answer:
Therefore it will take 7.66 hours for 80% of the lead decay.
Explanation:
The differential equation for decay is


Integrating both sides
ln A= kt+c₁

[
]
The initial condition is A(0)= A₀,


.........(1)
Given that the
has half life of 3.3 hours.
For half life
putting this in equation (1)

[taking ln both sides,
]

⇒k= - 0.21
Now A₀= 1 gram, 80%=0.8
and A= (1-0.8)A₀ = (0.2×1) gram = 0.2 gram
Now putting the value of k,A and A₀in the equation (1)




⇒ t≈7.66
Therefore it will take 7.66 hours for 80% of the lead decay.