An example of a crystalline substance that does not possess water of crystallization is
potassium trioxonitrate (V)
sodium tetraoxosulphate (VI).
iron (II) tetraoxosulphate (VI)
sodium trioxocarbonate (IV).
Correct answer is B
The chemical formula for sodium tetraoxosulphate (VI) is \(Na_2SO_4\). It is also known as sodium sulfate. This compound does not have any water molecules as part of its crystal structure, making it anhydrous. So, it is an example of a crystalline substance that does not possess water of crystallization.
Which of the following gases has the lowest rate of diffusion?
[H=1.0, C=12.0, N = 14.0, O= 16.0]
Nitrogen
methane
Ammonia
Oxygen
Correct answer is D
The rate of diffusion of a gas is inversely proportional to the square root of its molar mass (Graham's law). This means that gases with a higher molar mass will diffuse more slowly than gases with a lower molar mass. Given the molar masses of the gases in the options, Oxygen (O=16.0) has the highest molar mass and therefore the lowest rate of diffusion
Isoelectronic species have the same number of
ions
electrons
protons
neutrons
Correct answer is B
The term "isoelectronic" comes from the Greek words "iso" meaning "equal" and "electron" meaning "electron". Isoelectronic species are atoms, molecules, or ions that have the same number of electrons. have the same number of electrons because they have the same electron configuration. The electron configuration of an atom is the arrangement of electrons in the atom's orbitals. The electron configuration of an atom determines the chemical properties of the atom.
Why are \(H_2SO_4\) and \(CaCl_2\), not suitable for drying ammonia gas? They
are poisonous.
pollute the gas
are corrosive
react with the gas
Correct answer is D
\(H_2SO_4\) and \(CaCl_2\) are not suitable for drying ammonia gas because they react with the gas.
Ammonia is a basic gas, and both \(H_2SO_4\) and \(CaCl_2\) are acidic. When these two substances react, they form salts that contain ammonia. This can contaminate the ammonia gas and make it unusable.
In addition, \(H_2SO_4\) is a corrosive substance, and \(CaCl_2\) can be harmful to breathe in. Therefore, it is not safe to use these substances to dry ammonia gas.
\(Zn_{(s)} → Zn^{2+}_{(aq)} + 2e^-\)
\(CuSO_{4(s)} + H_2O_{(l)}\) → \(Cu^{2+}_{(aq)}\) + \(SO_{4(aq)}^{2-}\)
\(Cu^{2+}_{(aq)} + 2e^- → Cu_{(s)}\)
\(Cu^{2+}_{(aq)} + e^- → Cu_{(s)}\)
Correct answer is C
The reduction half equation for the given reaction is:
\(Cu^{2+}_{(aq)} + 2e^- → Cu_{(s)}\)
In the overall reaction, copper(II) ions (\(Cu^{2+})\) gain two electrons (2e^-) and get reduced to form solid copper (Cu) metal. This is the reduction half-reaction in the redox reaction between zinc (Zn) and copper(II) sulfate (\(CuSO_4)\).