Which model of the atom was able to explain both the bright-line spectrum of the hydrogen atom and also aspects of chemical bonding?

Mole measure the number of elementary entities of a given substance that are present in a given sample. 3 mole of Cr are in 156 g of the element. The correct option is option B.

What is mole?

The SI unit of amount of substance in chemistry is mole. The mole is used to measure the quantity or amount of substance. We know one mole of any element contains 6.022×10²³ atoms which is also called Avogadro number.

Mathematically, mole and molar mass of chromium can be related as :

number of mole =given mass of chromium÷ molar mass of chromium

Mass of chromium=156 g

Molar mass of 1 mole of chromium= 51.9961 g/mol

Substituting the given values we get,

number of mole =156 g ÷  51.9961 g/mol

number of mole= 3

Therefore, the correct option is option B. 3 mole of Cr are in 156 g of the element.

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You are given the number of grams of Chromium which is 156 grams. The molar mass of chromium is 52 grams per mole. Divide 156 grams to 52 grams per mole of Chromium and you will get 3 moles of Chromium. The answer is letter B.

Answer:

proton and neutron

Explanation:

proton is positive while neutron is neutral so they can live togher

Explanation:

To balance the chemical equation for the extraction of iron from iron(III) oxide using carbon, you need to ensure that the same number of each type of atom appears on both sides of the equation. Here's the balanced equation:

2Fe₂O₃ + 3C -> 4Fe + 3CO

Now, let's determine which substance is oxidized and which is reduced:

1. Iron (Fe) undergoes a change in oxidation state from +3 in iron(III) oxide (Fe₂O₃) to 0 in elemental iron (Fe). It is reduced because it gains electrons, going from a higher positive oxidation state to zero.

2. Carbon (C) in carbon (C) undergoes a change in oxidation state from 0 to +2 in carbon monoxide (CO). Carbon is oxidized because it loses electrons and goes from an oxidation state of 0 to +2.

So, in this chemical reaction:

- Iron is reduced (it gains electrons).

- Carbon is oxidized (it loses electrons).

Answer:the correct options are A (H⁺(aq)) and E (Mg₃(PO₄)₂(s)).

Explanation:To determine which substances are present in the net ionic equation for the reaction between MgCl2(aq) and H3PO4(aq), we first need to write the balanced molecular equation and then separate it into ions to identify the spectator ions. Spectator ions are those ions that do not participate in the chemical reaction and remain unchanged.

First, let's write the balanced molecular equation:

MgCl2(aq) + 2H3PO4(aq) -> Mg3(PO4)2(s) + 6HCl(aq)

Now, let's break down the equation into ions:

Mg²⁺(aq) + 2Cl⁻(aq) + 2H₃PO₄(aq) -> Mg₃(PO₄)₂(s) + 6H⁺(aq) + 6Cl⁻(aq)

Now, let's identify the spectator ions, which are the ions that appear on both sides of the equation and do not change:

- Mg²⁺(aq) is present on both sides.

- Cl⁻(aq) is present on both sides.

So, the spectator ions are Mg²⁺(aq) and Cl⁻(aq).

Now, let's determine the substances that are part of the net ionic equation, excluding the spectator ions:

Net Ionic Equation: 2H₃PO₄(aq) -> Mg₃(PO₄)₂(s) + 6H⁺(aq)

From the net ionic equation, the following substances are present:

A. H⁺(aq)

E. Mg₃(PO₄)₂(s)

So, the correct options are A (H⁺(aq)) and E (Mg₃(PO₄)₂(s)).

The other ions and compounds do not participate directly in the net ionic reaction and are spectator ions.