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ad-work [718]
3 years ago
11

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

Chemistry
2 answers:
siniylev [52]3 years ago
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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Which statement explains the energy term in this reaction
lana66690 [7]

Answer:

Mass is lost due to the conversion of mass to energy

Explanation:

The question is not complete, the complete question is given as:

        ^{235}_{72}U +^{1}_{0}n                       ⇒        ^{140}_{56}Ba+^{93}_{36}Kr+3^{1}_{0}n+energy

total mass equals 236.053 u              total mass equals 235.868 u

Which statement explains the energy term in this reaction? (1) Mass is gained due to the conversion of mass to energy. (2) Mass is gained due to the conversion of energy to mass. (3) Mass is lost due to the conversion of mass to energy. (4) Mass is lost due to the conversion of energy to mass.

Answer: From Einstein’s equation  E = mc², when a radioisotope element undergoes fission or fusion in a nuclear reaction, it loses a tiny amount of mass.This mass lost is converted to energy.

The law of conservation of energy  holds for this type of reaction (i.e  the sum of mass and energy is remains the same in a nuclear reaction). Mass changes to energy, but the total amount of mass and energy combined remains the same before and after a nuclear reaction.

From the reaction above, the total decrease in mass = 236.053 - 235.868 = 0.185 u

4 0
3 years ago
3- Um tipo de nutriente complexo presente
umka21 [38]

Answer:

The human body when metabolizing meat, milk or eggs, being high in protein, manufactures uric acid as a metabolite, and releases more urea in the urine.

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Gout disease is systemic and life-threatening puffiness.

Furthermore uric acid is an organic compound of carbon, nitrogen, oxygen and hydrogen. Its chemical formula is C5H4N4O3. It is found in urine in small amounts.

And urea is defined as a renal parameter from the quantitative point of view; It is a colorless, crystalline chemical compound of formula CO (NH2) 2. It is found abundantly in urine and faeces.

Explanation:

To have an accurate idea of the function of the kidneys, it is sufficient to carry out a simple blood test with determination of Urea and creatinine and an analysis of a urine sample in which the presence of cells (red blood cells and leukocytes) is assessed. and / or proteins (albumin). Today these 2 types of analysis are part of the routine of any analytical study.

4 0
3 years ago
A mineral forms in water heated by magma inside Earth.
allsm [11]

Answer:

the mineral formed when a hot water solution cooled

4 0
3 years ago
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The form of oxygen that combines three oxygen atoms to each molecule, is found in the stratosphere and shields out harmful UV ra
Dmitry_Shevchenko [17]
This form of the oxygen molecule is Ozone, O3.

7 0
3 years ago
How many molecules are in 21.5G of water
NemiM [27]

Answer:

There are 6.022×1023 molecules in a mole. There are 18.01528 grams of water per mole of water. in 1g water

Explanation:

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6 0
2 years ago
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