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3 years ago

If Z is the symbol for an element, which pair among the following represents isotopes of the same element?

Chemistry

2 answers:

insens350 [35]3 years ago

5 0

the answer is B. got this correct on the test

anygoal [31]3 years ago

3 0

B. 51 50
Z and Z
25 25

It is because only this element have equal number of Protons (Bottom number) and are different in atomic masses (upper number)

Hope this helps!

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Consider a mixture of two gases, A and B, confined in a closed vessel. A quantity of a third gas, C, is added to the same vessel

n200080 [17]

The question is incomplete, here is the complete question:

Consider a mixture of two gases, A and B, confined in a closed vessel. A quantity of a third gas, C, is added to the same vessel at the same temperature. How does the addition of gas C affect the following. The mole fraction of gas B?

A mixture of gases contains 10.25 g of N₂, 2.05 g of H₂, and 7.63 g of NH₃.

Answer: The mole fraction of gas B (hydrogen gas) is 0.557

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

For nitrogen gas:

Given mass of nitrogen gas = 10.25 g

Molar mass of nitrogen gas = 28 g/mol

Putting values in equation 1, we get:

$\text{Moles of nitrogen gas}=\frac{10.25g}{28g/mol}=0.366mol$

For hydrogen gas:

Given mass of hydrogen gas = 2.05 g

Molar mass of hydrogen gas = 2 g/mol

Putting values in equation 1, we get:

$\text{Moles of hydrogen gas}=\frac{2.05g}{2g/mol}=1.025mol$

For ammonia gas:

Given mass of ammonia gas = 7.63 g

Molar mass of ammonia gas = 17 g/mol

Putting values in equation 1, we get:

$\text{Moles of ammonia gas}=\frac{7.63g}{17g/mol}=0.449mol$

Mole fraction of a substance is given by:

$\chi_A=\frac{n_A}{n_A+n_B+n_C}$

Moles of gas B (hydrogen gas) = 1.025 moles

Total moles = [0.366 + 1.025 + 0.449] = 1.84 moles

Putting values in above equation, we get:

$\chi_{(H_2)}=\frac{1.025}{1.84}=0.557$

Hence, the mole fraction of gas B (hydrogen gas) is 0.557

6 0

3 years ago

Matter that has a uniform and defined composition is called a

Fittoniya [83]

Answer - A substance is matter that has a uniform and definite composition. All samples of substances, sometimes called pure substances, have identical properties.

6 0

3 years ago

How many significant figures are in the number 0.00230? O 6

EleoNora [17]

Answer:

0.00230 = 3 significant figures

Explanation:

Significant digits or figures of a given number are the digits or figures that have meaning and contributes to the precision of the given number.

Therefore, 0.00230 = 3 significant figures.

Reason: The non-zeros figures and the trailing zero after the decimal are significant. Whereas, all the leading zeros are not considered significant.

4 0

3 years ago