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.
Answer:
B. Water will freeze
<em>because</em><em> </em><em>the</em><em> </em><em>latent</em><em> </em><em>heat</em><em> </em><em>of</em><em> </em><em>vapourization</em><em> </em><em>decreases</em><em>.</em>
Answer :- Electrical energy
Explanation :-
Geothermal energy is too large scale
solar energy is inefficient
Nuclear does more harm
Answer: 3 <span>moles of water would be produced in present case.
</span>
Reason:
Reaction involved in present case is:
<span> C5H12 + 8O2 </span>→<span> 5CO2 + 6H2O
In above reaction, 1 mole of C5H12 reacts with 8 moles of oxygen to give 6 moles of water.
Thus, 4 moles of oxygen will react with 0.5 mole of C5H12, to generate 3 moles of H2O.</span>
Answer:
KI
Explanation:
From the question, we can see that a qualitative analysis of the compound shows that it has a lilac flame colour. The lilac flame colour corresponds to the potassium ion (K^+).
Again, the test of addition of HNO3(aq) and AgNO3(aq) to a solution is a test for halogens. If the result is a green precipitate, then the ion present is the iodide ion (I^-).
Hence, the compound must be KI.
