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.
Carbon-6 because it is a neutron number
The first and Third graph
Explanation:
The reaction expression is given as;
2H₂
+ O₂ → 2H₂O
From the balance reaction expression:
2 mole of hydrogen gas combines with 1 mole of oxygen gas on the reactant side;
This produces 2 mole of water on the product side of the expression.
The product is in liquid form.
This reaction is a synthesis reaction because a single product is formed from two reactants.
The answer is B. This is because Sodium has 1 valence electron and Fluorine has 7 valence electrons. All elements want 8 valence electrons so they may be stale, like the noble gases are. Hope this helps.
