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arsen [322]
3 years ago
10

An atom of 40 18 Ar has a nucleus that contains a total of

Chemistry
2 answers:
melisa1 [442]3 years ago
5 0
Atoms are composed of protons, electrons, and neutrons. so, answer D can be discarded because it is not what atoms are made of. 

40 and 18 represent the atomic mass and atomic number respectively. the atomic number presents the number of protons. so there are 18 protons. the number of neutrons can be determined by taking the atomic mass minus the atomic number. neutrons= 40-18= 22 neutrons.

so the answer is B

Answer A may be correct if we assume the atom is neutral. in a neutral atom, the number of protons is the same as the number of electrons. but the electrons are not in the nucleus but orbiting it. the question specified the nucleus.
Cloud [144]3 years ago
4 0
The correct answer is b, 18 protons
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Which of the following is an electrolyte?<br><br> a. PbCl2<br> b. MgS<br> c. HNO3<br> d. Al2(Cr2O7)3
Phoenix [80]

Answer: A: PbCl2

Hope dis helps!

8 0
3 years ago
What is the relationship between the amount of substance ( concentration) and reaction rates?
jekas [21]

Answer:

Increasing the concentration of the reagents makes the collision between two molecules of the reagents more likely, thereby increasing the probability that the reaction will occur between these reagents.

As for the relationship between concentration and volume, density also comes into play, a higher volume, lower molarity and also lower concentration.

The pressure when increasing could generate a closer approach between the particles, therefore generating an increase in the reaction speed.

Pressure and volume are related but inversely proportional, therefore if the volume increases the pressure decreases and so on.

the reaction rate increases as the contact surface area increases. This is due to the fact that more solid particles are exposed and can be reached by reactant molecules.

A perfect reaction where the collision is promoted and the reaction speed advances is with the presence of a solvent, with an increase in pressure and a decrease in volume, with an increase in the exposure of the surface, with the presence of a catalyst, with increasing temperature and with increasing entrance

Explanation:

The reaction rate is defined as the amount of substance that is transformed into a certain reaction per unit of volume and time. For example, the oxidation of iron under atmospheric conditions is a slow reaction that can take many years but over time it is oxidized sooner or later by the oxygenation of its surface layer, but the combustion of butane in a fire is a reaction that happens in fractions of seconds, giving rise to an exothermic reaction with products such as CO2 and H2O

5 0
3 years ago
When aqueous solutions of manganese(II) iodide and sodium phosphate are combined, solid manganese(II) phosphate and a solution o
Feliz [49]

Answer:

The net ionic equation for the given reaction :

3Mn^{2+}(aq)+2PO_4^{3-}(aq)\rightarrow Mn_3(PO_4)_2(s)

Explanation:

3MnI_2(aq)+2Na_3PO_4_2(aq)\rightarrow Mn_3(PO_4)_2(s)+6NaI(aq)...[1]

MnI_2(aq)\rightarrow Mn^{2+}(aq)+2I^-(aq)..[2]

Na_3PO_4(aq)\rightarrow 3Na^{+}(aq)+PO_4^{3-}(aq)...[3]

NaI(aq)\rightarrow Na^+(aq)+I^-(aq)

Replacing MnI_2(aq) , NaI and Na_3PO_4(aq) in [1] by usig [2] [3] and [4]

3Mn^{2+}(aq)+6I^-(aq)+6Na^{+}(aq)+2PO_4^{3-}(aq)\rightarrow Mn_3(PO_4)_2(s)+6Na^+(aq)+6I^-(aq)

Removing the common ions present ion both the sides, we get the net ionic equation for the given reaction [1]:

3Mn^{2+}(aq)+2PO_4^{3-}(aq)\rightarrow Mn_3(PO_4)_2(s)

8 0
3 years ago
When copper metal is added to nitric acid, the following reaction takes place
zlopas [31]

Answer:

The volume of NO₂ gas collected over water at 25.0 °C is 1.68 Liters.

Explanation:

Cu (s) + 4 HNO_3 (aq) \rightarrow Cu(NO_3)_2 (aq) + 2 H_2O (l) + 2 NO_2 (g)

Moles of copper = \frac{2.01 g}{63.55 g/mol}=0.03163 mol

According to reaction, 1 mol of copper gives 2 moles of nitrogen dioxide gas.

Then 0.03613 moles of copper will give:

\frac{2}{1}\times 0.03163 mol=0.06326 mol of nitrogen dioxide gas

Moles of nitrogen dioxide gas = n = 0.06326 mol

Pressure of the gas = P

P = Total pressure - vapor pressure of water

P = 726 mmHg - 23.8 mmHg = 702.2 mmHg

P = 0.924 atm (1 atm = 760 mmHg)

Temperature of the gas = T = 25.0°C =298.15 K

Volume of the gas = V

PV=nRT

V=\frac{0.06326 mol\times 0.0821 atm L/mol K\times 298.15 K}{0.924 atm}

V = 1.68 L

The volume of NO₂ gas collected over water at 25.0 °C is 1.68 Liters.

3 0
3 years ago
Why do you think we are able to study the atom in the modern world?
andriy [413]
Advancement in technology to help with detailed studies
6 0
2 years ago
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