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3 years ago

Element X had a mass of 300g and a 1/2 life of 10 years. how many grams will remain after 40 years?

Chemistry

1 answer:

kiruha [24]3 years ago

3 0

<h3>Answer:</h3>

18.75 grams

<h3>Explanation:</h3>

Half-life refers to the time taken by a radioactive material to decay by half of the original mass.
In this case, the half-life of element X is 10 years, which means it takes 10 years for a given mass of the element to decay by half of its original mass.
To calculate the amount that remained after decay we use;

Remaining mass = Original mass × (1/2)^n, where n is the number of half-lives

Number of half-lives = Time for the decay ÷ Half-life

= 40 years ÷ 10 years

= 4

Therefore;

Remaining mass = 300 g × (1/2)⁴

= 300 g × 1/16

= 18.75 g

Hence, a mass of 300 g of an element X decays to 18.75 g after 40 years.

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Two molecules of one reactant combine with 3 molecules of another to produce 5 molecules of a product.

maksim [4K]

Answer:

A = 2A + 3B → 5C

Explanation:

The two molecule of A and three molecules of B will react to form the five molecules of C.

2A + 3B → 5C

Other options are incorrect because,

B = A₂ + B₃ → C₅

in this reaction one molecule of A₂ and one molecule of B₃ combine to form one molecule of C₅.

C = 2A + 5B → 3C

in this reaction two molecules of A and five molecules of B combine to form three molecule of C.

D = A₂ + B₃ → C₃

in this reaction one molecule of A₂ and one molecule of B₃ combine to from one molecule of C₃.

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3 years ago

PLEASE HELP ME I NEED HELP

Crazy boy [7]

Answer:

<u>5 moles S x (36.02 g S/mole S) = 180.1 grams of S</u>

Explanation:

The periodic table has mass units for every element that can be correlated with the number of atoms of that element. The relationship is known as Avogadro's Number. This number, 6.02x $10^{23}$ , is nicknamed the mole, which scientists found to be a lot more catchy, and easier to write than 6.02x $10^{23}$ . <u>The mole is correlated to the atomic mass of that element.</u> The atomic mass of sulfur, S, is 36.02 AMU, atomic mass units. <u>But it can also be read as 36.02 grams/mole.</u>

<u></u>

<u>This means that 36.02 grams of S contains 1 mole (6.02x</u> $10^{23}$ <u>) of S atoms</u>.

<u></u>

This relationship holds for all the elements. Zinc, Zn, has an atomic mass of 65.38 AMU, so it has a "molar mass" of 65.38 grams/mole. ^5.38 grams of Zn contains 1 mole of Zn atoms.

And so on.

5.0 moles of Sulfur would therefore contain:

(5.0 moles S)*(36.02 grams/mole S) = <u>180.1 grams of S</u>

Note how the units cancel to leaves just grams. The units are extremely helpful in mole calculations to insure the correct mathematical operation is done. To find the number of moles in 70 g of S, for example, we would write:

(70g S)/(36.02 grams S/mole S) = 1.94 moles of S. [<u>Note how the units cancel to leave just moles</u>]

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2 years ago

How many single covalent bonds can halogens form?

Simora [160]

One single covalent bond, hope this helps!

4 0

3 years ago

The process of an atom releasing energy when it moves to a lower energy state is called

Inga [223]

The process of an atom releasing energy when it moves to a lower energy state is called emission.

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