Since this equation is balanced, we know that the law of conversation of mass id applied, and we could calculate easily.
Na= 2
NO3= 2
Ca= 1
<span>Cl= 1</span>
Answer: half life
Explanation: Radioactive decay follows first order kinetics and the time required for the decay of a radioactive material is calculated as follows:

t= time required
k= disintegration constant
x= amount of substance left after time t
a= initial amount of substance
when one half of the sample is decayed, one half of the sample remains and t can be represented as 
at
, 


Water has h bonding
H-H
Sodium fluoride
I think
Answer:
1.023 J / g °C
Explanation:
m = 37.9 grams
ΔT = 25.0*C
H = 969 J
c = ?
The equation relating these equation is;
H = mcΔT
making c subject of formulae;
c = H / mΔT
c = 969 J / (37.9 g * 25.0*C)
Upon solving;
c = 1.023 J / g °C