kg and all the given units are units used to measure mass.
kg is the standard unit to measure mass
lets find the value of 0.00684 kg in all the given units
a. dkg
1 kg is equivalent to 100 decagram (dkg)
therefore 0.00684 kg is = 100 dkg/kg x 0.00684 kg = 0.684 dkg
this is not the given value therefore this choice is incorrect
b. 1 kg is equivalent to 1000 g
therefore 0.00684 kg = 1000 g/kg x 0.00684 kg = 6.84 g
this is the given value so this is correct
c. 1 kg is equivalent to 100 000 centigrams (cg)
therefore 0.00684 kg = 100 000 cg/kg x 0.00684 kg = 684 cg
this is the given value so this is also correct
d) 1 kg is equivalent to 1 000 000 mg
therefore 0.00684 kg = 1 000 000 mg/kg x 0.00684 kg = 6 840 mg
this too is correct
the incorrect answer is A. 0.0684 dkg
Answer:
Know this
1mole of a substance contains 6.022x10²³molecules
Now
8.55x10^-15moles x 6.022x10²³molecules/1mole
=5.15x10^9molecules.
Answer:
The answer of 1×10 -8 is 2
Q1. The answer is 3 minutes.
Let's first calculate the remaining amount in percent:
If 960g is 100 percent (starting amount), 30 g is how many percents:
960 g : 100% = 30 g : x
x = 30 g * 100% / 960 g = 3.125% = 0.03125
Now, using the formula to calculate the number of half-lives:
(1/2)ⁿ = x,
where
x is the remaining amount: x = 0.03125
n is the number of half-lives
1/2 stands for half-life.
(1/2)ⁿ = 0.03125
⇒ n*log(1/2) = log(0.03125)
n = log(0.03125)/log(1/2) = log(0.03125)/log(0.5) = -1.505/-0.301 ≈ 5
The number of half-lives is 5.
Now, <span>the number of half-lives (n) is a quotient of total time elapsed (T) and length of half-life (L):
n = T/L
We know:
n = 5
T = 15 min
L = ?
Thus
L = T/n
L = 15 min/5 = 3 minutes
Q2. Filtration should be chosen.
Filtration and distillation are used to separate mixtures - filtration for the separation of heterogeneous mixtures and </span>distillation for the separation of homogeneous mixtures. Imagine that your pile of soil is a mixture. It consists of different components (the leaves, acorns, twigs), so it is the heterogeneous mixture. Therefore, to separate the leaves, acorns, twigs you will use filtration.
<span> under extreme heat or pressure
crystallize from magma
precipitate from a solution reaction of hot mixture with water and a dissolved substance</span>
