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andriy [413]
3 years ago
11

Plsss help this midterm ends 12.30

Chemistry
1 answer:
Alona [7]3 years ago
5 0

Answer:

We know that,

Density= mass upon volume.

mass= 21.93g

Volume= 49.3 - 46.3

= 3 cm³

Density = 21.93÷ 3

= 7.31 g/cm³

Hope it helps :))

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E. The element 231/90Th decays to 231/91 Pa. Use the laws of conservation of charge and nucleon number to determine the decay pa
svetoff [14.1K]

Answer:

A negatron emission

Explanation:

We know that radioactivity orginates from instability of the nucleus. When the nucleus is unstable, radioactive emissions are produced in the form of any of these rays:

> Alpha particle emisson

>Beta particles

> Gamma rays

These emissions create a balance for a radioactive decay.

In balancing nuclear reactions we make sure that the charges on both sides must be conserved and that the mass number and atomic numbers conserved too. This means that the sum of mass number and atomic numbers on both side of the reaction must be equal.

The nucleons are the protons and neutrons, they add up to give the mass number. The atomic number is the proton number.

For the given radioactive reaction:

²³¹₉₀Th → ²³¹₉₁Pa + ?

From this equation, we see that the mass number is conserved but the atomic number is not.

The mass number is the superscript whereas the atomic number is the subscript.

Let's say the decay produces an emission of a particle denoted by X

²³¹₉₀Th → ²³¹₉₁Pa + ᵃₙX

What would the nature of X be?

For the charges and masses to be conserved, X must have mass number of 0 and an atomic number of -1.

Checking:

Mass number:

231 = 231 + a ( a is the mass number)

a = 231 - 231 = 0

Atomic number:

90 = 91 + n

n = 90- 91 = - 1

With X having a mass number of 0 and an atomic number of -1, we have a beta particle emission. Specifically, a negatron has been emitted.

A negatron is denoted as ⁰₋₁β which perfectly makes the equation conserved and suits the description of X.

The complete equation is thus written as:

²³¹₉₀Th → ²³¹₉₁Pa + ⁰₋₁β + energy

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3H₂SO₄ + 2Al₂(SO₄)₃  → Al₂(SO₄)₃ + 3H₂ is the balanced chemical equation that represents a single displacement reaction.

<h3>What is a balanced chemical equation?</h3>

The equation in which the number of atoms of all the molecules is equal on both sides of the equation is known as a balanced chemical equation.

3H₂SO₄ + 2Al₂(SO₄)₃  → Al₂(SO₄)₃ + 3H₂

In this type of reaction, one substance is replacing another:

A + BC  →  AC + B

In a single displacement reaction, atoms replace one another based on the activity series. Elements that are higher in the activity series. Also, if the element that is to replace the other in a compound is more reactive the reaction will occur. If it is less reactive, there will be no reation.

In the first equation, fluorine is more reactive than bromine. Therefore, bromine cannot replace bromine.

In the second equation, the displacement is between hydrogen and aluminium. Hydrogen is lower in the activity series, this implies that aluminium will replace it.

Hence, 3H₂SO₄ + 2Al₂(SO₄)₃  → Al₂(SO₄)₃ + 3H₂ is the balanced chemical equation that represents a single displacement reaction.

Learn more about the displacement reaction here:

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Explanation: Hope this helped!!!!

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Answer:

The metalloids; boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te), polonium (Po) and astatine (At) are the elements found along the step like line between metals and non-metals of the periodic table.

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Explanation:

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