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matrenka [14]
4 years ago
8

Which of the following definitions characterizes an element?

Chemistry
1 answer:
Amanda [17]4 years ago
6 0
<span>The answer is A because an elements only consists of one type of atom. Example. the element H (hydrogen) only contains 1 hydrogen atom. I hope this helps!! </span>
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Provide a brief description of how the respiratory system works
Rus_ich [418]

Answer:

The lungs and respiratory system allow oxygen in the air to be taken into the body, while also letting the body get rid of carbon dioxide in the air breathed out. When you breathe in, the diaphragm moves downward toward the abdomen, and the rib muscles pull the ribs upward and outward.

Explanation:

3 0
3 years ago
1.How many moles of each element are in 0.0250 mol of K 2 Cr O 4? 2. How many moles of ammonium ions are in 4.50 mol of (N H 4 )
noname [10]

Answer:

1. 0.0500 moles K, 0.0250 moles Cr and 0.1000 moles O.

2. 9.00 moles ammonium ions are present.

Explanation:

1. In 1mol of K2CrO4 there are 2 moles of K, 1 mole of Cr and 4 moles of O.

The moles in 0.0250 moles K2CrO4 are:

0.0250mol * 2 = 0.0500 moles K

0.0250mol * 1 = 0.0250 moles Cr

0.0250mol * 4 = 0.1000 moles O

2. In 1 mole of (NH4)2CO3 there are 2 moles of ammonium ions, NH₄⁺.

In 4,50 moles are:

4.50 moles * 2 = 9.00 moles ammonium ions are present

5 0
3 years ago
A balloon is filled with 30L of helium gas at 1atm.What is the volume when balloon rises to an attitude where the pressure is on
Harrizon [31]

Answer:

V_2=120L

Explanation:

Hello!

In this case, since Helium is undergoing a volume-pressure change, according the Boyle's law, we infer the following equation is used:

P_1V_1=P_2V_2

Thus, since we are not given the volume at 0.25 atm, we can solve for V2 to do so:

V_2=\frac{P_1V_1}{P_2}

Thus, we plug in to obtain:

V_2=\frac{1atm*30L}{0.25atm}=120L

Best regards!

7 0
3 years ago
Calculate the Ka for a 0.3 M solution of HA (unknown weak acid) if the pH = 3.65. The reaction can be modelled as HA (aq) + H2O
Levart [38]

The Ka : 1.671 x 10⁻⁷

<h3>Further explanation</h3>

Given

Reaction

HA (aq) + H2O (l) ←→ A- (aq) + H3O+ (aq).

0.3 M HA

pH = 3.65

Required

Ka

Solution

pH = - log [H3O+]

\tt [H_3O^+]=10^{-3.65}=2.239\times 10^{-4}

ICE method :

HA (aq)        ←→   A- (aq)    +    H3O+ (aq).

0.3                           0                 0

2.239.10⁻⁴           2.239.10⁻⁴   2.239.10⁻⁴

0.3-2.239.10⁻⁴    2.239.10⁻⁴    2.239.10⁻⁴

\tt Ka=\dfrac{[H_3O^+][A^-]}{[HA]}\\\\Ka=\dfrac{(2.239.10^{-4}){^2}}{0.3-2.239.10^{-4}}\\\\Ka=1.671\times 10^{-7}

5 0
3 years ago
What is the purpose of adding the concentrated phosphoric acid to the reaction
9966 [12]

Answer:

its a catalyst to make the reaction faster

Explanation:

persianutabcom

5 0
2 years ago
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