Perform the following calculation and report each answer with the correct number of significant figures.
(a) 628 x 342
(b) (5363 x 102) x (7.4 x 103)
(c) 28.0/13.483
(d) 8119 x 0.23
(e) 14.98 + 27,340 + 84.7593
(f) 42.7 + 0.259

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.

(a) 628 × 342

The correct answer is,

(b) (5363 × 102) × (7.4 × 103)

The correct answer is,

(c) 28.0 ÷ 13.483

The correct answer is, 2.08

(d) 8119 × 0.000023

The correct answer is,

(e) 14.98 + 27,340 + 84.7593

The correct answer is,

(f) 42.7 + 0.259

The correct answer is,

points

explanation:

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol