4. What is the rarest element that is natural to earth?

Chemistry

2 answers:

krek1111 [17]3 years ago

5 0

Astatine it’s also a chemical element

never [62]3 years ago

3 0

Answer:

Astatine

Explanation:

Astatine is a chemical element with the symbol At and atomic number 85. It is the rarest naturally occurring element in the Earth's crust, occurring only as the decay product of various heavier elements.

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What is the reaction between an acid and a base

galina1969 [7]

They create salt when put together

6 0

4 years ago

CARBOHYDRATES are found primarily in plant-based foods and are a major source of energy in the body (4 kcals per gram). If you c

SVETLANKA909090 [29]

Answer:

The 200 grams of carbohydrate would this convert to 800 kcals in a day.

Explanation:

Carbohydrates are the source of energy. The metabolism of 1 gram of carbohydrates gives 4 kcals of energy.

If 200 grams of carbohydrate is consumed in a day, then the energy provided by it is:-

$Energy\ provided\ by\ the\ carbohydrate = 200\times 4\ kcals=800\ kcals$

<u>The 200 grams of carbohydrate would this convert to 800 kcals in a day.</u>

4 0

3 years ago

All of the following conditions of STP are true except A. 101.3 kPa B. 273.15 K C. 22.4 L D. 3.81 kPa

kaheart [24]

3.81 kpa is the condition which is not true at STP

According to IUPAC the standard temperature and pressure that is STP the temperature is 273.15 k or 0 degrees celsius . and the absolute temperature of 101.325 Kpa or 1 atm. In addition at STP the volume of ideal gas is 22.4

8 0

4 years ago

2 NaCL + CaO = CaCL2 + Na2O

Naily [24]

222 grams of calcium chloride is produced.

<h3><u>Explanation</u>:</h3>

The mole concept and the chemical equation are very much closely related with each other. In the chemical reaction, the compounds or elements in both sides are balanced according to the number of atoms of each side of the reaction. So from there we can easily find the amount of reactant reacts to produce desired product.

Here we can see that 2 moles of sodium chloride produces 1 mole of calcium chloride.

So, 4 moles of sodium chloride will produce 2 moles of calcium chloride.

Now, atomic weight of calcium =40.

Atomic weight of chlorine =35.5.

So,the molecular weight of calcium chloride = $40+ 35.5\times2$