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sertanlavr [38]

2 years ago

13

An atom of elements x has one more shell of electrons than an atom of beryllium,but h are s one less valence electron then beryl

lium.which element is element X?

1 answer:

Ilia_Sergeevich [38]2 years ago

5 0

Element X is sodium.

If there is one more shell of electrons, then this means it is one period below.

Since there is one less valence electron, it is one group to the left.

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The average atomic mass of Eu is 151.96 amu. There are only two naturally occurring isotopes of europium, Eu with a mass of 151.

earnstyle [38]

Answer:

The percentage abundance of Eu isotopes are 52 % and 48 % .

Explanation:

The formula for the calculation of the average atomic mass is:

$Average\ atomic\ mass=(\frac {\%\ of\ the\ first\ isotope}{100}\times {Mass\ of\ the\ first\ isotope})+(\frac {\%\ of\ the\ second\ isotope}{100}\times {Mass\ of\ the\ second\ isotope})$

Given that:

Since the element has only 2 isotopes, so the let the percentage of first be x and the second is 100 -x.

For first isotope,:

% = x %

Mass = 151.0 amu

For second isotope :

% = 100 - x

Mass = 153.0 amu

Given, Average Mass = 151.96 amu

Thus,

$151.96=\frac{x}{100}\times {151.0}+\frac{100-x}{100}\times {153.0}$

Solving for x, we get that:

x = 52 %

<u>Thus percentage abundance of Eu isotopes are 52 % and 48 % .</u>

7 0

3 years ago

If the formula for a compound is represented by X3Y2 and the charge on the Y ion is -3, what is the charge in the X ion?

artcher [175]

I cannot fully remember but the charge of a compound always has to be the same. However, I believe that the sign of the Y2 means that it is positive 2.

so in my opinion it is in between b and c. use your best judgment.

3 0

2 years ago

What diffuses more quickly: tetracarbon decahydride (C4H10) or iodine (12)? By how much?

ValentinkaMS [17]

Answer: Butane will effuse more quickly because it has a smaller molar mass

Explanation:

Molar mass of C4H10 = 58.123 g/mole

Molar mass of I2 = 253.808 g/mole

5 0

3 years ago

What mass of NH4NO3 would you need to make 250.0mL of a 0.78M solution?

katrin [286]

Answer:

a

Explanation:

8 0

3 years ago

Read 2 more answers

A gas tank contains 3 gases (N2, O2, and CO2). The total pressure of the gases is 825mmHg. If Pco2 = 125mmHg and Po2= 350mmHg, w

DedPeter [7]

Answer:

350mmHg

Explanation:

Use Dalton law

Total=P gas 1+p gas 2+ P gas 3

825=P1+350+125

825=P1+475

825-475= P1

P1= 350 mm Hg

3 0

2 years ago