<h3>Because it is harmful for school environment.</h3>
Potassium Metal Is Explosive— Do Not Use It! The reaction of sodium with water is a spectacular and essential classroom demonstration. Many teachers want to show also the more violent reaction of potassium. We propose not to do so because explosions can happen even before the metal is in contact with water.
<em>-</em><em> </em><em>BRAINLIEST</em><em> answerer</em>
growing only enough crops for food to fed the family
Explanation:
subsistence farming is the practice of growing crops only for own use .. some developing countries are only doing farming for their personal use so they are in the stage of developing ..in a country like nepal we not being able to trade our farming .if we want to export then also we arenot getting the good market ..
194.5 g of BCl₃ is present in 1 × 10²⁴ molecules of BCl₃.
Explanation:
In order to convert the given number of molecules of BCl₃ to grams, first we have to convert the molecules to moles.
It is known that 1 moles of any element has 6.022×10²³ molecules.
Then 1 molecule will have
moles.
So 
Thus, 1.66 moles are included in BCl₃.
Then in order to convert it from moles to grams, we have to multiply it with the molecular mass of the compound.
As it is known as 1 mole contains molecular mass of the compound.
As the molecular mass of BCl₃ will be

Mass of boron is 10.811 g and the mass of chlorine is 35.453 g.
Molar mass of BCl₃ = 10.811+(3×35.453)=117.17 g.


So, 194.5 g of BCl₃ is present in 1 × 10²⁴ molecules of BCl₃.
The answer for four is frequency.
The oceanic part of the earth is the liquid portion Of the planet