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3 years ago

Can someone help me on this please ?

Chemistry

1 answer:

lesya [120]3 years ago

6 0

If it’s 22.5 millimeters, it’s gonna be 22,500 micrometers. The answer is C

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A solution of 0.0027 M K2CrO4 was diluted from 3.00 mL to 100. mL. What is the molarity of the new solution?

Stells [14]

Answer:

[K₂CrO₄] → 8.1×10⁻⁵ M

Explanation:

First of all, you may know that if you dilute, molarity must decrease.

In the first solution we need to calculate the mmoles:

M = mmol/mL

mL . M = mmol

0.0027 mmol/mL . 3mL = 0.0081 mmoles

These mmoles of potassium chromate are in 3 mL but, it stays in 100 mL too.

New molarity is:

0.0081 mmoles / 100mL = 8.1×10⁻⁵ M

4 0

2 years ago

If you have 222 g of radioisotope with a half-life of 5 days, how much isotope would remain after 15 days?

Dima020 [189]

If the half life is 5 days, you would have to divide 222 by 2 3 times.
so 222/2 =111g
111/2 = 55.5g
55.5/2 = 27.75g

after four half life the mass would be
27.75/2
13.875g

the percent would be
13.875/222
= 6.25%

7 0

3 years ago

a sample of an oxide of antimony (sb) contain 19.75 g of antimony combine with 6.5 g of oxygen . what is the simplest formula fo

frez [133]

Explanation:

The given data is as follows.

Mass of antimony = 19.75 g

Molar mass of Sb = 121.76 g/mol

Therefore, calculate number of moles of Sb as follows.

Moles of Sb = $\frac{mass}{\text{molar mass}}$

= $\frac{19.75 g}{121.76 g/mol}$

= 0.162 mol

Mass of oxygen given is 6.5 g and molar mass of oxygen is 16 g/mol. Hence, moles of oxygen will be calculated as follows.

Moles of oxygen = $\frac{mass}{\text{molar mass}}$

= $\frac{6.5 g}{16 g/mol}$

= 0.406 mol

Hence, ratio of moles of Sb and O will be as follows

Sb : O

$\frac{0.162}{0.162} : \frac{0.406}{0.162}$

1 : 2.5

We multiply both the ratio by 2 in order to get a whole number. Therefore, the ratio will be 2 : 5.

Thus, we can conclude that the empirical formula of the given oxide is $Sb_{2}O_{5}$ .

4 0

2 years ago

20 POINTS 2 QUESTIONS CAN YOU ANSWER THEM ???

Viktor [21]

2. <span>1/8 = (1/2)³ </span>
<span>so it's 3 half lives.</span>

7 0

2 years ago

Read 2 more answers

What happens to frequency as wavelength

castortr0y [4]

Answer:

B. Frequency decreases

4 0

3 years ago