If two different liquids are mixed with equal volumes there density is 9 g/cc and if the same liquids mixing in the equal masses then density is 8 g/cc find individual densities of two liquids
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If two liquids are mixed in equal volumes, their resultant density is 5 gr/cc and mixed in equal masses their resultant density is 4.8 g/cc . The ratio of their densities is
k
2
.Then K is
Medium
Solution
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Correct option is
B
3
Let the densities be D
1
and D
2
Density=
Volume
Mass
Case 1 : Equal Volume
⟹M
1
=D
1
×V
and
M
2
=D
2
×V
Density combined =
2V
(M
1
+M
2
)
=
2
(D
1
+D
2
)
=5
⟹D
1
+D
2
=10
Case 2 : Equal Masses
⟹V
1
=
D
1
M
⟹V
2
=
D
2
M
Density combined =
(M/D
1
+M/D
2
)
2M
=
(D+1+D
2
)
2D
1
D
2
=4.8
10
D
1
×D
2
=2.4
⟹D
1
×D
2
=24
impliesD
1
(10−D
1
)=24
⟹−D
1
2
+10D
1
=24
⟹D
1
2
−10D
1
+24=0
⟹D
1
2
−6D
1
−4D
1
+24=0
⟹(D
1
−6)(D
1
−4)=0
Then,
D
1
=6 or 4
D
2
are 4&6
D
2
D
1
=
4
6
=
2
3
is not of form
k
2
while
D
2
D
1
=
6
4
=
3
2
=
k
2
⟹k=3
Answer:
Let the specific gravities of the two substances be S1 and S2 , and the density of water at 4∘C be ρ .
So, densities of the substances are S1ρ and S2ρ .
Let V be the volume of each of the substances in the mixture.
So, the total mass of the mixture is (VS1ρ+VS2ρ) .
And, the total volume of the mixture is (V+V)=2V .
So, according to the problem, the specific gravity of the mixture is,
S1+S22=4
or, S1+S2=8 …(1).
Again, let m be the mass of each of the two substances in the mixture.
So, the total mass of the mixture is (m+m)=2m .
And, the total volume of the mixture is (mS1ρ+mS2ρ) .
So, the density of the mixture is,
2mmS1ρ+mS2ρ=2S1S2ρS1+S2
So, according to the problem, the specific gravity of the mixture is,
2S1S2S1+S2=3
or, S1S2=32(S1+S2)=32×8=12
So, (S1−S2)=(S1+S2)2−4S1S2−−−−−−−−−−−−−−−√=(8)2−(4×12)−−−−−−−−−−−−√=4 …(2).
From equation (1) , S1=8−S2,
Putting this value in equation (2) , we get, S2 = 2 .
2 .And, putting this value in either of the equations, we get, S1 = 6 .