Q: Calculate the average atomic mass of silver if it has two naturally occurring isotopes with the following masses and natural abundances: $$\displaystyle \text{Ag-107: } 106.90509\ \text{amu, } 51.84\%$$ $$\displaystyle \text{Ag-109: } 108.90476\ \text{amu, } 48.16\%$$ What is the average atomic mass?

$$\displaystyle 107.87\ \text{amu}$$

Q: Determine the density of an object that has a mass of $$\displaystyle 13.8\ \text{g}$$ and displaces $$\displaystyle 12.1\ \text{mL} of $$water when placed in a graduated cylinder.

$$\displaystyle 1.14\ \text{g/mL}$$

Q: How many milliliters (mL) are in $$\displaystyle 63.01$$ nanoliters (nL)? $$\displaystyle 1\ \text{mL} = 10$$^{6}$$\ \text{nL}$$

$$\displaystyle 6.301 \times 10$$^{-5}$$\ \text{mL}$$

Q: How many milligrams (mg) are in $$\displaystyle 120.12$$ kilograms (kg)?

$$\displaystyle 1.2012 \times 10$$^{8}$$\ \text{mg}$$

Q: Which nuclide symbol correctly labels the isotope of lithium with mass 7 amu and atomic number 3?

$$\$$displaystyle ^{7}$$_{3}\text{Li}$$

Question 1

A student measures the length of a metal bar as 15.60 cm. How many significant figures are in this measurement?

Accepted Answer

4

Question 2

What does the 'X' represent in the isotope symbol $$\displaystyle \frac{28}{14}X$$?

Accepted Answer

Silicon (Si)

Question 3

Calculate the average atomic mass of silver if it has two naturally occurring isotopes with the following masses and natural abundances:

$$\displaystyle 	ext{Ag-107: } 106.90509\ 	ext{amu, } 51.84\%$$
$$\displaystyle 	ext{Ag-109: } 108.90476\ 	ext{amu, } 48.16\%$$

What is the average atomic mass?

Accepted Answer

$$\displaystyle 107.87\ 	ext{amu}$$

Question 4

Magnesium belongs to which group of elements?

Accepted Answer

Alkaline earth metal

Question 5

Which of the following elements has the largest atomic radius?

Accepted Answer

Na

Question 6

How many significant figures are in $$\displaystyle 1.650 	imes 10$$^{3}$$?

Accepted Answer

4

Question 7

Determine the density of an object that has a mass of $$\displaystyle 13.8\ 	ext{g}$$ and displaces $$\displaystyle 12.1\ 	ext{mL} of $$water when placed in a graduated cylinder.

Accepted Answer

$$\displaystyle 1.14\ 	ext{g/mL}$$

Question 8

Choose the element from the list below that is a noble gas.

Accepted Answer

Argon

Question 9

Choose the homogeneous mixture from the list below.

Accepted Answer

Carbonated soda

Question 10

Which statement about subatomic particles is correct?

Accepted Answer

Neutrons and protons are both found in the nucleus of the atom.

Question 11

What particle is emitted when $$\$$displaystyle ^{90}$$	ext{Sr}$$ decays radioactively to $$\$$displaystyle ^{90}$$	ext{Y}$$?

Accepted Answer

Beta

Question 12

Which orbital diagram represents the ground state of nitrogen (N)?

Accepted Answer

1s: \uparrow\downarrow, 2s: \uparrow\downarrow, 2p: \uparrow\uparrow\uparrow

Question 13

A penny has a measured mass of $$\displaystyle 3.119\ 	ext{g}. $$Class A reports an average mass of $$\displaystyle 3.121\ 	ext{g}$$ with a standard deviation of $$\displaystyle 0.004\ 	ext{g}$$, and Class B reports $$\displaystyle 3.133\ 	ext{g}$$ with a standard deviation of $$\displaystyle 0.007\ 	ext{g}. $$Which class was more accurate?

Accepted Answer

Class A

Question 14

How many milliliters (mL) are in $$\displaystyle 63.01$$ nanoliters (nL)?

$$\displaystyle 1\ 	ext{mL} = 10$$^{6}$$\ 	ext{nL}$$

Accepted Answer

$$\displaystyle 6.301 	imes 10$$^{-5}$$\ 	ext{mL}$$

Question 15

How many milligrams (mg) are in $$\displaystyle 120.12$$ kilograms (kg)?

Accepted Answer

$$\displaystyle 1.2012 	imes 10$$^{8}$$\ 	ext{mg}$$

Question 16

Is it easier to remove an electron from beryllium or magnesium? Explain why.

Accepted Answer

Magnesium, because it has a lower ionization energy due to its larger atomic radius.

Question 17

Below is the mass spectrum of lithium. How many isotopes of lithium are in the sample?

Accepted Answer

2

Question 18

Which nuclide symbol correctly labels the isotope of lithium with mass 7 amu and atomic number 3?

Accepted Answer

$$\$$displaystyle ^{7}$$_{3}	ext{Li}$$

Question 19

Without performing any calculations, predict the approximate atomic mass for lithium based on the mass spectrum showing peaks at 6 amu (relative intensity 8) and 7 amu (relative intensity 100).

Accepted Answer

Slightly less than 7 amu

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