Answer:
The correct answer would be - 13.0975 ounces.
Explanation:
We know that brass is made up of zinc and copper. The copper part of the brass is approximately around 50 to 70% and the remaining is the zinc part.
Given:
Zinc percentage in a brass = 35%
copper percentage would be - 65% (100 - 35 = 65)
Weight of the brass metal bar = 20.15 ounce
ounces of copper are in the bar = ?
Solution:
The weight of the copper in the brass metal in ounces-
= weight of brass* percentage of copper/100
= 20.15*65/100
= 13.0975 ounces of copper.
2nd method =
The weight of the zinc in the brass metal in ounces-
= weight of brass* percentage of zinc/100
= 20.15*35/100
= 7.0525
The weight of the copper = total weight - weight of zinc
= 13.0975 ounces of copper.
Answer 1
The sample will dissolve in more than 1 minute.
Explanation :-
Generally Solubility and rate of solubility of substances increase with the increase in temperature. So lower the temperature less fast will it dissolve in the same amount of water.
Since at 50 C it takes 1 minute to dissolve, at 20 C which is lower temperature it will take more time to dissolve.
Answer 2
Transition metals
Explanation:-
Hardness depends on the extent of metallic bonding for metals. More the number of electrons more the metallic bonding.
Alkali metals with just 1 valence electron have weak metallic bonding. Alkaline earth metals have just 2 valence electrons. Transition elements has more electrons in penultimate shell and valence shell than lanthanides. Transition metals with most metallic bonding are the hardest
3 Pb(NO₃)₂ + 2 AlCl₃ → 3 PbCl₂ + 2 Al(NO₃)₃
<span>
from balanced reaction , 3 moles of Pb(NO</span>₃<span>)</span>₂<span> required to produce 3 moles PbCl</span>₂<span>, 3:3 </span>
<span>
8 moles PbCl</span>₂<span> x (3/3) = 8 moles Pb(NO</span>₃<span>)</span>₂<span> required</span>