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3 years ago

Which of these elements has the lowest melting point? (1) Li (3) K (2) Na (4) Rb

2 answers:

4 0

The answer is (4) Rb. From observation, we can find that these four elements are from first column. The melting point from top to the bottom is from high to low. So the answer is (4).

natali 33 [55]3 years ago

4 0

Answer: Option (4) is the correct answer.

Explanation:

It is known that on moving down a group there will be decrease in melting point of the element because of increase in number of shells.

As a result, outermost electrons move away from the nucleus due to which there will be decrease in force of attraction between the protons and valence electrons. Hence, there will be decrease in melting point.

Therefore, the given elements are of same group and Rb has largest atomic size.

Thus, we can conclude that Rb has the lowest melting point.

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State 2 postulates of kinetic theory of gases of 45 of 450

Ber [7]

Explanation:

The kinetic theory of gases is basically used to explain the behavior of gases.

Some of the assumptions of the theory is as follow:

A gas is composed of large number of identical molecules at different speeds.
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The molecules are independent of each other and the force of attraction and repulsion between them are negligible.
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3 years ago

26. At high temperatures these elements conduct electricity but at lower temperatures they do not conduct electricity. This make

LenaWriter [7]

A semiconductor conducts electricity at high temperatures, but not at low temperatures. At high temperatures, metalloids act like metals and conduct electricity.

Explanation:

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4 0

3 years ago

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Eva8 [605]

It decreases it's temperature and it take about 10 hours for it to decrease

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3 years ago

Global winds are directly caused by the Earth's rotation and

Natali5045456 [20]

Answer:

A the uneven heating of earths surface

Explanation:

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3 years ago

What would be the major product obtained from hydroboration–oxidation of the following alkenes?

zmey [24]

Answer:

a. 3-methylbutan-2-ol

b. 2-methylcyclohexan-1-ol

Explanation:

For this reaction, we must remember that the hydroboration is an "anti-Markovnikov" reaction. This means that the "OH" will be added at the least substituted carbon of the double bond.

In the case of 2-methyl-2-butene, the double bond is between carbons 2 and 3. Carbon 2 has two bonds with two methyls and carbon 3 is attached to 1 carbon. Therefore the "OH" will be added to carbon three producing 3-methylbutan-2-ol.

For 1-methylcyclohexene, the double bond is between carbons 1 and 2. Carbon 1 is attached to two carbons (carbons 6 and 7) and carbon 2 is attached to one carbon (carbon 3). Therefore the "OH" will be added to carbon 2 producing 2-methylcyclohexan-1-ol.

See figure 1

I hope it helps!

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3 years ago