# Question 903d4

Jul 4, 2017

$9. \left(\text{D}\right)$

$10. \left(\text{B}\right)$

$11. \left(\text{A}\right)$

$12. \left(\text{B"), ("B}\right)$

#### Explanation:

$9.$ The number of significant figures in $70.60$ $\text{mph}$ is $4$.

The number of significant figures in any number is really how many digits it contains.

One thing to bear in mind is that if the number begins with a $0$, it should not be counted towards the number of significant figures.

For example, $0.35$ has $2$ significant figures, but $3.50$ has $3$ significant figures.

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$10.$ In order to find percent error, we can use this formula: frac(|"Experimental value " - " actual value"|)(|"Actual value"|) times 100%

Rightarrow "Percent error" = frac(|9.53 " g / cm"^(3) - 9.78 " g / cm"^(3)|)(|9.78 " g / cm"^(3)|) times 100%

Rightarrow "Percent error" = frac(|- 0.25 " g / cm"^(3)|)(|9.78 " g / cm"^(3)|) times 100%

Rightarrow "Percent error" = frac(0.25 " g / cm"^(3))(9.78 " g / cm"^(3)) times 100%

Rightarrow "Percent error" = 0.02556237219 times 100%

therefore "Percent error" approx 2.5 %

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$11.$ In this question, we need to find the density of the green jade sample.

The density of any object is the quotient of its mass and volume, i.e. "density" = frac("mass")("volume").

We already have the mass of the jade sample (5.25 "g"), but we need to find its volume.

The graduated cylinder was initially filled with $50.0$ $\text{ml}$ of water, but after placing the sample in it, the water level rose to $60.5$ $\text{ml}$.

The difference between these two volumes is the volume of the jade sample:

$R i g h t a r r o w \text{Volume of jade sample} = 60.5$ $\text{ml}$ $-$ $50.0$ $\text{ml}$

$\therefore \text{Volume of jade sample} = 10.5$ $\text{ml}$

Now, let's use plug all relevant values into the density formula:

Rightarrow "Density of jade sample" = frac(5.25 " g")(10.5 " ml")

$\therefore \text{Density of jade sample} = 0.50$ $\text{g / ml}$

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$12.$ The first question asks us to assess which substance $\underline{\text{cannot}}$ be drawn into a wire.

A substance's property of being drawn into a wire is known as ductility.

According to the table, sulfur is $\underline{\text{not}}$ ductile, so it $\underline{\text{cannot}}$ be drawn into a wire.