Calculate the percentage composition of oxygen in calcium trioxocarbonate(IV) [Ca=40, C=12, O=16]
16
48
40
12
Correct answer is B
Calcium trioxocarbonate (IV) = CaCO\(_3\)
Percentage of Oxygen = \(\frac{\text{Molar mass of 3O}}{\text{Molar mass of} CaCO_3}\) × 100%
Percentage of Oxygen = \(\frac{(3 \times 16)}{(40 + 12 + 48)}\) x 100%
Percentage of Oxygen = \(\frac{48}{100}\) x 100%
Percentage of Oxygen = 48%
The ionic radii of metals are usually
greater than their atomic radii
unaffected by the charge on the ion
the same as their atomic radii
less than their atomic radii
Correct answer is D
In a neutral atom, the atomic and ionic radius is the same, but many elements exist as anions or cations. If the atom loses its outermost electron (positively charged or cation), the ionic radius is smaller than the atomic radius because the atom loses an electron energy shell.
Yes ionic radius is only less than atomic radius for a metal.
In electrovalency, the oxidation number of the participating metal is always
decreasing
increasing
constant
neutral
Correct answer is B
In electro-valency the oxidation number of the participating metal increases.
The derivative of benzene that can be used in making explosives is
aniline
xylene
phenol
toluene
Correct answer is D
Yes, Toluene is used in making explosives, based on information from the textbook "New School Chemistry", pg 541.
Phenol is used as a starting material to makes explosive materials such as picric acid. Picric acid is one of the most acidic phenol. Like other strongly nitrated organic compounds, picric acid is an explosive. Toluene, however, is used to produce a stronger explosive material called TriNitroToluene (TNT).
Therefore Toluene is the most appropriate answer for this question but in situations where you don't find Toluene in the options provided, then Phenol makes a viable answer.
the litmus turns blue but no gas is evolved
the litmus turns blue and oxygen is evolved
the litmus turns blue and hydrogen is evolved
the litmus turns red and oxygen is evolved
Correct answer is D
During the electrolysis of copper using platinum electrode, Cu and H migrate to the cathode while,SO\(_4\) and OH migrate to the anode.CU is then discharged preferentially at the cathode, acquiring two electrons and is deposited as metallic copper, while OH is discharged preferentially at the anode and deposited as gaseous oxygen, then the SO\(_4\) and H still in the solution react, thereby making d solution acidic and then changing the litmus paper red which is the test for acids.