Which of the following describes the chemical property of acids?
None of the above
Acid + XCO\(_3\) \(\to\) Salt + H\(_2\)O + NH\(_3\)
Acid + NaOH \(\to\) Normal salt + CO\(_2\)
Acid + X\(_n\)CO\(_3\) \(\to\) Salt + H\(_2\)O + CO\(_2\)
Correct answer is D
No explanation has been provided for this answer.
Which of the following pollutants will lead to the depletion of ozone layer?
chlorofluorocarbon
carbon (ii) oxide
hydrogen sulphide
sulphur (iv) oxide
Correct answer is A
No explanation has been provided for this answer.
Which two gases can be used for the demonstration of the fountain experiment?
SO\(_4\) and NH\(_3\)
SO\(_3\) and NH\(_3\)
HCl and NH\(_3\)
SO\(_2\) and CO
Correct answer is C
No explanation has been provided for this answer.
75,000 particles
35,000 particles
25,000 particles
50,000 particles
Correct answer is C
Given:
t\(\frac{1}{2}\) = 20 years
After the first 20 years, half of the substance (\(\frac{1}{2} \times 100,000 = 50,000\)) will have decayed. Hence, we have 100,000 - 50,000 = 50,000 particles left.
After the second 20 years (being 40 years in all), half of the remaining substance (\(\frac{1}{2} \times 50,000 = 25,000\)) will have decayed.
Remaining particles after 40 years = 50,000 - 25,000
= 25,000 particles.
5
7
3
9
Correct answer is C
Methyl orange is the best indicator for the reaction with range 3.1 - 4.4.