### Significant Digits – Chemistry Chapter 1 Quiz

This quiz covers significant digits – Chemistry Chapter 1 Quiz

Multiply or divide the following measurements. Be sure each answer you enter contains the correct number of significant digits.

**Correct Answers**

**770.6g ÷ 0.42mL = 1.8 x 10 ^{3 }g/mL**

**7.81cm × 3.30cm = 25.8cm ^{2}**

**940.85g ÷ 54.2mL = 17.4g/mL**

Add or subtract the following measurements. Be sure each answer you enter contains the correct number of significant digits.

**Correct Answers**

**2.500mL + 10.97mL = 13.47mL**

**17.97mL + 9.7mL = 27.7mL**

**18.50mL − 12.7mL = 5.8mL**

Complete the table below.

**Correct Answers**

**70 dL = 7 L**

**2 Mg = 2,000,000 g**

**3 ks = 3000 s**

**2000 mm = 2 m**

A molecular biologist measures the mass of cofactor A in an average yeast cell. The mass is 96.7 pg. What is the total mass in micrograms of cofactor A in a yeast colony containing 10^{5} cells? Write your answer as a decimal.

**9.67 µg** **– Correct **

A geologist measures the height of a mountain. The height is 3.8749 km. What is the height in meters? Write your answer as a decimal.

**3874.9 m – Correct**

A student sets up the following equation to convert a measurement.

(The ? stands for a number the student is going to calculate.) Fill in the missing part of this equation.

**(0.010 g/mL).(1mL/10 ^{-3}L) = ? g/L**

**– Correct**

Multiply or divide the following measurements. Be sure each answer you enter contains the correct number of significant digits.

**Correct Answers**

**561.00mol ÷ 0.90L = 6.2 x 10 ^{2} mol/L**

**93.4g/mL × 47.mL = 4.4 x 10 ^{3} g**

**294.77mol ÷ 43.02L = 6.852 mol/L**

A student sets up the following equation to convert a measurement.

(The ? stands for a number the student is going to calculate.)Fill in the missing part of this equation.

**(-4.7 x 10 ^{3} N/cm).(1 cm/10^{-2} m).(10^{-3} m/1 mm) = ? N/mm –**

**Correct**

There are four sketches below. The first sketch shows a sample of Substance X. The three sketches underneath it show three different changes to the sample. You must decide whether each of these changes is possible. If a change is possible, you must also decide whether it is a physical change or a chemical change.

Each sketch is drawn as if the sample were under a microscope so powerful that individual atoms could be seen. Also, you should assume that you can see the entire sample, and that *the sample is in a sealed box*, so that no matter can enter or leave.

Experiments were done on a certain pure substance *X* to determine some of its properties. There’s a description of each experiment in the table below.

In each case, decide whether the property measured was a chemical or physical property of *X*, if you can. If you don’t have enough information to decide, choose *can’t decide* in the third column.

Complete each row of the table below by filling in the missing prefix or missing exponent.

Simplify the following expression.

−3*x*^{2} + 5 + 11*x*^{2} − 7*x*

**8x ^{2} − 7x + 5**

**–**

**Correct**

Simplify.

x^{-6}. x^{-8}

Write your answer with a positive exponent only.

**1/x ^{14}**

**– Correct**

What would the mystery charge labeled “?” have to be for this object to have a net electric charge of +1 ?

*Note for advanced students:* you can assume charge is measured in any convenient units, e.g. coulombs or units of e. Write down only the number part of your answer.

Each sketch below shows three objects with an electric charge. In each case, decide whether there is a net force acting on the object outlined in green. If there *is* a net force, decide whether it pushes the green-ring object to the left or right. Then select the appropriate button under the sketch.

For example, if there is a net force pushing the green-ring object in the first sketch to the left, select the left button under the first sketch. If there is no net force on the green-ring object in the second sketch, select the middle button under the second sketch. And so on.

The net electric force acting on each of the three objects below is sketched as a green arrow. For example, if the green arrow points to the left the object feels a net electric force pushing it to the left. If there is no green arrow, the object feels no net electric force.

Use this information to assign an electric charge to each object. That is, decide whether each object has a positive electric charge, a negative electric charge, or is neutral.*Note for advanced students*: there may be more than one correct answer.