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2 3 is what i would put
The much of the sample that would remain unchanged after 140 seconds is 2.813 g
Explanation
Half life is time taken for the quantity to reduce to half its original value.
if the half life for Scandium is 35 sec, then the number of half life in 140 seconds
=140 sec/ 35 s = 4 half life
Therefore 45 g after first half life = 45 x1/2 =22.5 g
22.5 g after second half life = 22.5 x 1/2 =11.25 g
11.25 g after third half life = 11.25 x 1/2 = 5.625 g
5.625 after fourth half life = 5.625 x 1/2 = 2.813
therefore 2.813 g of Scandium 47 remains unchanged.
The mole fraction of helium is 0.33.
The mole fraction can be calculated with the aid of dividing the number of moles of 1 factor of an answer by means of the overall number of moles of all the additives of a solution. it's far noted that the sum of the mole fraction of all the components in the solution should be same to one.
Mole fraction is a unit of attention. within the answer, the relative amount of solute and solvents are measured by the mole fraction and it is represented. The mole fraction is the wide variety of moles of a specific thing within the solution divided by way of the entire wide variety of moles.
Mole fraction represents the quantity of molecules of a selected thing in a combination divided by using the total variety of moles within the given mixture. it is a manner of expressing the concentration of a solution. consequently, the sum of mole fraction of all of the additives is always equal to one.
Mole of neon = 1
mole of helium = 2
mole of argon = 3
Total mole = 1 + 2 + 3 = 6
Mole fraction = mole of helium / total mole
= 2 / 6 = 0.33
Learn more about mole fraction here:-brainly.com/question/1601411
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The fire triangle is composed of
1) heat
2) fuel
3) oxidizing agent (oxygen)
Types of fire extinguishers:
1) Water and Foam - <span> extinguish the fire by taking away the </span>heat<span> element of the fire triangle. Foam agents separate the </span>oxygen<span> element from the other elements.</span>
2) Carbon dioxide - <span>extinguish fire by taking away the </span>oxygen<span> element of the fire triangle and also be removing the </span>heat<span> with a very cold discharge.</span>
3) Dry Chemical - <span>extinguish the fire primarily by interrupting the </span>chemical reaction<span> of the fire triangle.</span>
4) Wet Chemical - <span>extinguishes the fire by removing the heat of the fire triangle and prevents re-ignition by creating a barrier between the </span>oxygen<span> and </span>fuel<span> elements</span>
5) Clean Agent - <span>extinguish the fire by interrupting the </span>chemical reaction<span> of the fire triangle</span>
6) Dry Powder - extinguish the fire by separating thefuel<span> from the </span>oxygen<span> element or by removing the </span>heat<span> element of the fire triangle</span>
7) Water Mist - <span>extinguish the fire by taking away the </span>heatelement of the fire triangle
8) Cartridge Operated Dry Chemical - extinguish the fire primarily by interrupting the chemical reaction<span> of the fire triangle</span>
