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a_sh-v [17]
3 years ago
7

Which statement concerning elements is true?(1) Different elements must have different numbers of isotopes.

Chemistry
1 answer:
Marina86 [1]3 years ago
4 0
The correct statement is <span>(4) All atoms of a given element must have the same atomic number.

Atoms come in different isotopes(which have different mass), which differ in the number of neutrons, but are still the same element (this tells you why the other options are bad).
</span>
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The International Date Line
geniusboy [140]

Answer:

The International Date Line, established in 1884, passes through the mid-Pacific Ocean and roughly follows a 180 degrees longitude north-south line on the Earth. It is located halfway round the world from the prime meridian—the zero degrees longitude established in Greenwich, England, in 1852.

8 0
2 years ago
Consider the elements: Na, Mg, Al, Si, P.
Olegator [25]

Answer:

The elements mentioned in the series are Na, Mg, Al, Si, and P. It can be seen that all these elements are located in the same period. The atomic number of the mentioned elements are Na-11, Mg-12, Al-13, Si-14, and P-15.

a) There will be an increase in the ionization energy with the increase in the element's atomic number across a period. More energy is needed to withdraw an electron from a completely occupied shell in comparison to an incompletely occupied shell.

The atomic number of Na is 11. When one electron is withdrawn from Na, it gets converted into the inert gas configuration of Ne. Thus, it will require more energy to withdraw the second electron from Na. Hence, Na exhibits the lowest second ionization energy.

b) Across the period, with an increase in the element's atomic number, the atomic radii reduces from left to right. Thus, P exhibits the smallest atomic radius.

c) The metallic nature of the elements reduces from left to right across a period in the periodic table. Thus, P is the least metallic element.

d) Diamagnetic signifies towards the element that exhibits pair electrons in its sub-shells. The electronic configuration of Mg is,

1s2 2s2 2p6 3s2

In Mg, no unpaired electrons are present, while all the remaining elements mentioned exhibit unpaired electrons in their valence shell. Thus, Mg is the diamagnetic element.

8 0
3 years ago
32.33 mL of 1.031 M potassium hydroxide were required to reach the endpoint of a titration of 50.00 mL of nitric acid. What was
tester [92]

The molar concentration of the nitric acid solution was 0.6666 mol/L.

<em>Balanced equation</em>: KOH + HNO_3 → KNO_3 + H_2O

<em>Moles of KOH</em>: 32.33 mL KOH × (1.031 mmol KOH /1 mL KOH)

= 33.33 mmol KOH

<em>Moles of HNO_3</em>: 33.33 mmol KOH× (1 mmol HNO_3/1 mmol KOH)

= 33.33 mmol HNO_3

<em>Concentration of KOH</em>: <em>c </em>= "moles"/"litres" = 33.33 mmol/50.00 mL

= 0.6666 mol/L

4 0
3 years ago
How many grams of magnesium metal will react completely with 5.2 liters of 4.0 M HCl? Show all of the work needed to solve this
N76 [4]
Answer:
mass = 242.372 grams

Explanation:
1- getting the number of moles of HCl:
molarity = number of moles of solute / liters of solution
4 = number of moles of HCl / 5.2
number of moles of HCl = 4 * 5.2 = 20.8 moles

2- getting the number moles of magnesium:
From the balanced equation given, we can note that one mole of magnesium is required to react with two moles of HCl. To get the number of moles required to react with 20.8 moles of HCl. we will simply do cross multiplication as follows:
1 mole of Mg ...............> 2 moles of HCl
?? moles of Mg ...........> 20.8 moles of HCl
Number of moles of Mg = 20.8 / 2 = 10.4 moles

3- getting the mass of Mg:
number of moles = mass / molar mass
Using the periodic table, we can find that the molar mass of magnesium is 24.305 grams.
This means that:
10.4 = mass / 24.305
mass = 24.305 * 10.4
mass = 242.372 grams

Hope this helps :)
3 0
2 years ago
Which is not an issue with waste from nuclear energy?
Mkey [24]

Answer:

correct option is A) atmospheric pollutants

Explanation:

  • Nuclear power plant do not produce air pollution in the form of carbon dioxide and sulfur dioxide.
  • Nuclear as radioactive waste is hazardous to all kind of life and the environment.
  • Long-term storage of radioactive waste is required. It is important that waste stabilization is a form that does not react or deteriorate for years.
  • If nuclear waste is wasted in the atmosphere or in the oceans and lagre lakes, it eventually comes into contact with organisms.
3 0
3 years ago
Read 2 more answers
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