
If the half-life of a sample of a radioactive substance is 30 seconds, how much would be left after 60 seconds? <span>
A. one-fourth</span>
Answer:
1.0
Explanation:
Hydrochloric acid is a strong acid, that is, an acid that dissociates completely, according to the following reaction.
HCl(aq) → H⁺(aq) + Cl⁻(aq)
Then, the concentration of H⁺ will be equal to the initial concentration of the acid, i.e., 0.10 M.
We can calculate the pH using the following expression.
pH = -log [H⁺] = -log 0.10 = 1.0
the poly atomic molecule is H2
The First 2 statements stated above were false whereas the third one is a true statement.
Explanation:
- The viscosity of bitumen is about 100 times greater than the viscosity of water - False
Reason - The viscosity of bitumen is about not 100 times greater than the viscosity of water, it is actually 100, 000 times greater.
- Oil from oil sand deposits is only obtained by first heating the sands at high temperatures is False.
Reason- Oil from oil sand deposits is not obtained by first heating the sands at high temperatures but by using steams
- Oil sands contain sand, water, and light crude oil is true.
The way you calculate the empirical formula is to firstly assume 100g. To find each elements moles you take each elements percentage listed, times it by one mole and divide it by its atomic mass. (ex: moles of K =55.3g x 1 mole/39.1g, therefore there is 1.41432225 moles of Potassium) Once you’ve completed this for every element you list each elements symbol beside it’s number of moles and divide by the smallest number because it can only go into its self once. After you’ve done this, you’ve found your empirical formula, which is the simplest whole number ratio of atoms in a compound. I’ve added an example of a empirical question I completed last semester :)