Question no 1:
Answer:
The correct answer is option C which is 2 × 1027.
Explanation:
Scientific notation is a way of expressing number which are very low or very short by expressing them in terms of power of 10.
(4× 105)(6 × 1023)/(1.2 × 102)
= 24× 1028/(1.2 × 102)
= 2× 1027
In terms of proper significant numbers, correct answer is 2× 1027.
Question 2.
Answer:
The correct answer is option C which is 5× 10-18.
Explanation:
Scientific notation is a way of expressing number which are very low or very short by expressing them in terms of power of 10.
Question: 7 × 10-8/(3 × 104)(5 × 105)
= 7 × 10-8/15 × 109
= 7 × 10-9 × 10-9/15
= 0.47 × 10-17
But in terms of significant figures and rounding off the decimal:
= 5 × 10-18
Hence the correct answer is option C. according to simple math calculations, all answers are correct but in terms of scientific notation and significant figures, only answer is option C.
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