### Step 1 of 3

Given data is about significant figures.

Here we found out the singnificant numbers by some rules.

**Explanation:**

We use the concept of significant figures. The final answer contains the numbers of significant figures as in given least significant figures digits.

### Step 2 of 3

Rules of determining significant figures.

- All non-zero digit are significate. e.g. 1.333 has 4 S.F. S.F.= Significant figures
- Final zeroes to the right of the decimal point are significant. e.g. 9.0 has 2 S.F.
- Zeroes found between two significant digits are significant. e.g. 1.0007 has 5 S.F.
- Any zero before a decimal point and before other significant digits is not significant. e.g. 0.132 has 3 S.F. and 0.0001352 has 4 S.F.
- Zeros between non-zero digits are significant. e.g. 107086 has 6 S.F.
- Any zero that are right of other digits in a whole number are not significant. e.g. 17000 has 2 S.F.

### Step 3 of 3

Part -A , Solution

1.75×10^{-3}/7.7×10^{2}=0.22727×10^{-5}=0.0000023=2.3×10^{-6} It has 2 S.F. Because 7.7 has 2 S.F.

So, it has two significant figures.

Part-B, Solution

1.94×10^{-2}+3×10^{-4}-3.4×10^{-3} Here we use the BODMAS rule in which first we solve divide term and second, we solve multiplication and after that addition term and in last we solve subtraction term.

1.94×10^{-2}+3×10^{-4}-3.4×10^{-3}=19.4× 10^{-3} + 0.30×10^{-3}-3.4×10^{-3}=19.7×10^{-3}-3.4×10^{-3}=16.3×10^{-3}=1.63×10^{-2}=1.6×10^{-2}

It has 2 S.F. as 0.30 has 2 S.F.

Part-C , Solution

(1.30×10^{5}) (0.000389)÷ (0.078) (116.5) = 50.57÷9.087=5.565=5.6 It has 2 S.F. as 0.078 has 2 S.F.

##### Final solution

In all part there are 2 S.F.