Answer:
Explanation:
because in air the particles are moving very fast and jar of coffee has hot particles which kinetic energy is also more so that's why it's particles move faster and gets mixed with air and smell is coming from far away
Answer:O D to protect the environment from harmful chemicals
Explanation:
<span>Well it depends on percentage by what, but I'll just assume that it's percentage by mass.
For this, we look at the atomic masses of the elements present in the compound.
Cu has an atomic mass of 63.546 amu
Fe has 55.845 amu
and S has 36.065 amu
Since there are 2 molecules of Sulfur for each one of Cu and Fe, we'll multiply the Sulfur atomic weight by 2 to obtain 72.13 amu
So we have not established the mass of the compound in amus
63.546 + 55.845 + 72.13 = 191.521
That is the atomic mass of Chalcopyrite. and Iron's atomic mass is 55.845
So to get the percentage, or fraction of iron, we take 55.845 / 191.521
Which comes out to 29.15% by mass
Mass of the sample is not needed for this calculation, but since the question mentions it I would go ahead and check if the question isn't also asking for the mass of Iron in the sample as well, in which case you just find the 29.15% of 67.7g</span>
Ni solution could be used to remove lead from lead (II) nitrate.
Explanation:
The removal of lead from lead nitrate will take place by displacement reaction.
In displacement reaction less reactive element is displaced by more reactive element form it compound.
The reactivity is decided by the placement of metal in the activity series.
A metal which is at higher position in the activity series will be able to displace the metal or element having lower position.
From the options given we will check their position in the activity series in comparison to Pb
Cu is lower in series than Pb hence cannot displace.
Hg is placed lower in the series than Pb hence cannot displace Pb.
Ag is placed lower than Pb in the series hence cannot displace Pb.
Ni is placed above the Pb in activity series hence can displace lead.
<span>Not all solids melt when they are heated. Some may undergo chemical changes as a result of heating. For example paper burns rather than melts</span>
