Question

Subtract 0.25 cm from 11.5 cm and round off the answer. A) 11.25 cm B) 11 cm C) 11.2 cm D) 11.3 cm E) 11.0 cm 5) Divide 11.375 g by 10.0 mL and round off the answer. A) 1.138 g/ml B) 1.14 g/mL C) 1.13 g/mL D) 1.1 g/ml E) 1.1375 g/mL 6) If a 125 mL Erlenmeyer flask weighs 88.5 g what is the volume in liters? A) 1.25 L B) 0.125 L C) 125,000 L D) 125 L E) none of the above

Answer 1

Answer:

First part: B) 11cm

Second part: B) $1.14\frac{g}{mL}$

Third part: B) 0.125L

Explanation:

First part: Subtract 0.25cm from 11.5cm and round off the answer.

You have two significant figures in 0.25, because zero is not a significant figure when is used to position de decimal point, and you have three significant figures in 11.5.

When you are subtracting numbers the result must have the smallest number of decimal places that the numbers you are subtracting, in this case, two significant figures:

11.5cm - 0.25cm = 11cm

Second part: Divide 11.375g by 10.0mL and round off the answer.

When you are dividing numbers the result must have the smallest number of significant figures that the numbers you are dividing:

11.375 has five significant figures

10.0 has three significant figures

$\frac{11.375g}{10.0mL}=1.14\frac{g}{mL}$

Note that the result of the division is 1.1375 but you have to round the three to the next integer so the number next to it, 7 is greater than 5.

Third part: If a 125mL Erlenmeyer flask weighs 88.5g what is the volume in liters?

There are 1000mL in 1 liter, so you have:

$125mL*\frac{1L}{1000mL}=0.125L$

Answer 2

Explanation:

• Subtraction is a process in which we minus smaller digit from a larger digit.

For example, we will subtract 0.25 cm from 11.5 cm as follows.

                  11.5 cm - 0.25 cm

                 = 11.25 cm

Hence, when we subtract 0.25 cm from 11.5 cm then we get 11.25 cm.

• Now, we will divide 11.375 g by 10.0 mL as follows.

                     $\frac{11.375 g}{10.0 ml}$

                  = 1.1375 g/ml

or,              = 1.14 g/ml (approx)

Therefore, when we divide 11.375 g by 10.0 mL then it is equal to 1.14 g/ml.

• We are given that volume of Erlenmeyer flask is 125 ml. And, we know that 1 ml is equal to 0.001 L.

Therefore, we will convert 125 ml into liter as follows.

                 $125 ml \times \frac{1 L}{1000 ml}$  

                  = 0.125 L

Thus, we can conclude that the volume of given flask in liters is 0.125 L.