Answer:
B) 2
Explanation:
Significant figures : The figures in a number which express the value -the magnitude of a quantity to a specific degree of accuracy is known as significant digits.
The rule apply for the multiplication and division is :
The least number of significant figures in any number of the problem determines the number of significant figures in the answer.
The rule apply for the addition and subtraction is :
The least precise number present after the decimal point determines the number of significant figures in the answer.
(3.478-2.31) = 1.168 ≅ 1.17 (Rounded to least decimal digit)
(4.428-3.56) = 0.868 ≅ 0.87 (Rounded to least decimal digit)
So,
1.17 * 0.87 = 1.0 (Rounded to least significant)
Answer - two significant digits
Melting? not really sure what type of answer they are going for but the substance is going through the melting phase
Renewable resource:wind
Nonrenewable resource: natural gas
Answer: It will take 3 days for half of a 10 g sample to decay.
Explanation:
Half-life of sample of an isotope X = 3 days
Sample decayed = 
N=
, time = t
![\ln[\frac{5}{10}]=-0.231\times t](https://tex.z-dn.net/?f=%5Cln%5B%5Cfrac%7B5%7D%7B10%7D%5D%3D-0.231%5Ctimes%20t)

t = 3 days
It will take 3 days for half of a 10 g sample to decay.