The required mass of calcium bromide is 35.98 grams.
<h3>What is molarity?</h3>
Molarity is any solution is define as the number of moles of solute present in per liter of solution as;
M = n/V, where
- M = molarity = 4M
- V = volume = 45mL = 0.045L
Moles will be calculated by using the above equation as:
n = (4)(0.045) = 0.18 mole
Relation between the mass and moles of any substance will be represented as:
n = W/M, where
- W = given mass
- M = molar mass
Mass of CaBr₂ = (0.18mol)(199.89g/mol) = 35.98g
Hence required mass of CaBr₂ is 35.98 grams.
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Answer: (E) 300 bq
Explanation:
Half life is the amount of time taken by a radioactive material to decay to half of its original value.
Radioactive decay process is a type of process in which a less stable nuclei decomposes to a stable nuclei by releasing some radiations or particles like alpha, beta particles or gamma-radiations. The radioactive decay follows first order kinetics.
Half life is represented by 
Half life of Thallium-208 = 3.053 min
Thus after 9 minutes , three half lives will be passed, after ist half life, the activity would be reduced to half of original i.e.
, after second half life, the activity would be reduced to half of 1200 i.e.
, and after third half life, the activity would be reduced to half of 600 i.e.
,
Thus the activity 9 minutes later is 300 bq.
Answer:- The direction of the polarity of the indicated bond is from carbon to oxygen.
Explanations:- There are two types of covalent compounds, polar and non polar. If the bond is between two same atoms for example, H-H, Cl-Cl etc then the bond is non polar. If the bond is between two different atoms then the bond would be polar. The direction of the polarity is from loss electron negative atom to more electron negative atom.
Oxygen is more electron negative than carbon. So, being more electron negative, the bonding electrons are more towards oxygen and it cases partial negative charge on oxygen and partial positive charge on carbon. The direction of the polarity is from less electron negative carbon to more electron negative oxygen.
It is shown in the diagram below:
To know the acidity of a
solution, we calculate the pH value. The formula for pH is given as:
<span>pH = - log [H+] where H+ must be in Molar</span>
We are given that H+ = 3.25 × 10-2 M
Therefore the pH is:
pH = - log [3.25 × 10-2]
pH = 1.488
Since pH is way below 7, therefore the solution
is acidic.
To find for the OH- concentration, we must
remember that the product of H+ and OH- is equivalent to 10^-14. Therefore,
[H+]*[OH-] = 10^-14 <span>
</span>[OH-] = 10^-14 / [H+]
[OH-] = 10^-14 / 3.25 × 10-2
[OH-] = 3.08 × 10-13 M
Answers:
Acidic
[OH-] = 3.08 <span>× 10-13 M</span>