Answer:
τ = - (8.1 N-m) i - (10.8 N-m) j - (8.1 N-m) k
Explanation:
Given
r = (0 m) i + (0.9 m) j - (1.2 m) k
F = (9 N) i + (0 N) j - (9 N) k
We can apply
τ = r x F
τ = ((0 m) i + (0.9 m) j - (1.2 m) k) x ((9 N) i + (0 N) j - (9 N) k)
⇒ τ = - (8.1 N-m) i - (10.8 N-m) j - (8.1 N-m) k
Answer:
Time taken 172.8 years
Explanation:
Given data:
Total amount of strontium-90 = 1000.0 g
Amount left = 15.625 g
Half life of strontium = 28.8 years
Time taken = ?
Solution:
Number of half lives:
At time zero = 1000.0 g
At first half life = 1000.0g/2 = 500 g
At second half life = 500 g/2 = 250 g
At third half life = 250 g/ 2 = 125 g
At 4th half life = 125 g/ 2= 62.5 g
At 5th half life = 62.5 g/2 = 31.25 g
At 6th half life = 31.25 g / 2 = 15.625 g
Time taken:
Time taken = number of half lives × half life
Time taken = 6×28.8 years
Time taken = 172.8 years
Answer:
The molarity of a solution is "25 M".
Explanation:
The given values are:
Moles of solute,
= 12.5 g
Volume of solution,
= 500 mL
i.e.,
= 0.5 L
Now,
The molarity will be:
= 
On substituting the values, we get
= 
= 
A mole is equivalent to 6.02 x 10^23 molecules at STP. Use a conversion factor like the following.
Example: The initial value x The value you are trying to convert to
------------------------------------------------
The value you are trying to get rid of
The correct answer is c, it’s evaporating there for it’s a chemical change
