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4 years ago

State whether the following statement is true.justify the answer with examples

Chemistry

1 answer:

Ilya [14]4 years ago

7 0

Answer:

False

Explanation:

Atoms only achieve complete outer electron shells if they contain an outer shell with 7 electrons before gaining another electron or an outer shell with 1 electron before losing an electron. This is assuming that the octet-rule can be applied to said atom. In addition, the number of valence electrons varies from atom to atom which is why not ALL atoms achieve complete outer electron shells after gaining or losing just ONE electron.

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Mass of 2×10^21 number of atoms of an element is 0.4g. What is the mass of 0.5 mole of the element?

alexandr402 [8]

Answer:

66.7 g

Explanation:

Number of atoms = 2×10²¹

Mass of 2×10²¹ atoms = 0.4 g

Mass of 0.5 moles of that element = ?

Solution:

1 mole contain 6.022×10²³ atoms

2×10²¹ atoms × 1 mol / 6.022×10²³ atoms

0.33×10⁻² mol

0.003 mol

0.003 mole have mass of 0.4 g

0.5 mol have mass 0.5/0.003×0.4 g = 66.7 g

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2 years ago

What is the atomic radius <br> of mercury?

cricket20 [7]

The answer is 155 pm, hope this helps!

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2 years ago

11. If there are 8.24 x 1022 molecules of NaCl in a salt shaker, what is the mass of the salt?

vlada-n [284]

Answer: 8.12 g NaCl

Explanation: Use Avogadro's number to find the number of m

moles of NaCl:

8.24x10²² molecules NaCl / 1 mole NaCl/ 6.022x10²³ molecules NaCl

= 0.14 mole NaCl

Next convert moles to grams NaCl using its molar mass;

0.14 mole NaCl x 58g NaCl / 1 mole NaCl

= 8.12 g NaCl

6 0

3 years ago

What is 1.5 x 10^3 in standard notation

LUCKY_DIMON [66]

1500 just move the decimal to the right three times because its a positive <span />

6 0

3 years ago

What is the percent of Cr in Cr2O3

IgorLugansk [536]

The percentage of Chromium in Chromium Oxide is calculated as follow,

Step 1:
Calculate Molar mass of Cr₂O₃,
Cr = 51.99 u
O = 16 u
So,
2(51.99) + 3(16) = 103.98 + 48 = 151.98 u

Step 2:
Secondly divide molar mass of only chromium with total mass of Cr₂O₃ and multiply with 100.
i.e.
= $\frac{103.98}{151.98}$ × 100

= 68.41 %
So, the %age composition of chromium in chromium oxide is 68.41 %.

5 0

3 years ago

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