____ family have three valence electrons.
The elements of boron family have ns2p1 configuration. This means that they have three valence electrons available for bond formation. By losing these electrons, they are expected to show +3 oxidation state. The first two elements of group 13, aluminium and boron elements show only +3 oxidation state in the compounds.
Coal gas is a mixture of:
Coal gas is a mixture of H2 + CO + CH4
____ is the ore of tin.
Cassiterite is the ore of tin. Cassiterite is tin stone having the formula SnO2. Anglesite, cerussite and galena are the ores of lead.
Thallium shows different oxidation states because
Thallium shows different (+1 and +3) oxidation states because of inert pair effect.
The hydrolysis of ____ followed by polymerization yields straight chain polymers.
The hydrolysis of dichlorodimethylsilane followed by polymerization yields straight chain polymers. When methyl chloride reacts with silicon in the presence of copper as a catalyst at 570 K, various types of methyl substituted chlorosilanes are formed. The hydrolysis of dichlorodimethylsilane followed by polymerization yields straight chain polymers.
Glass reacts with HF to produce
6HF + SiO2→H2SiF6 + 2H2O
Which among CH4, SiH4, GeH4, SnH4 is most volatile?
The lower the mol. Wt. The more is the volatile character.
Which of the following properties of aluminium makes it useful for food packaging?
Due to the low density of aluminium it is useful for food packaging.
When caustic soda is treated with aluminium hydroxide, the product formed is ____.
When caustic soda is treated with aluminium hydroxide, the product formed is NaAlO2. Al(OH)3 + NaOH ------------NaAlO2 + 2 H2O sodium meta aluminate.
The element of group 13 which forms only covalent compound is ____ .
The element of group 13 which forms only covalent compound is boron. Boron forms only covalent compounds because of the small size and high sum of first three ionisation energies.
Alum is not used
Alum is not used as an insecticide.
The highest concentration of gallium is found in ______________.
The highest concentration of gallium is found in germanite. Gallium, thallium and indium are less abundant than aluminium. Highest concentration of gallium (0.1 - 1%) is found in the rare mineral, germanite, which is a complex sulphide of Zn, Cu, Ge and As.
The ____ compound behaves as a superconductor below 18 K.
The fullerene compound behaves as a superconductor below 18 K. Below 18 K, it carries electric current with zero resistance.
White lead is
White lead is also called basic lead carbonate, Pb(OH)2.2PbCO3
____ is the principal oxide of boron.
The principal oxide of boron is boric acid. Heating orthoboric acid above 370 K leads to partial removal of water to yield metaboric acid, HBO2. Further heating first yields tetraboric acid, H2B4O7, and finally oric acid, B2O3, which is the principal oxide of boron.
Thermite is a mixture of
Thermite is mixture of Fe2O3 + Al.
Lead Pencil contains
Lead Pencil contains graphite.
____ is a mixture of the explosive nitrobenzene and kieselghur.
Gelignite is a mixture of the explosive nitrobenzene and kieselghur, which is an amorphous form of silica.
Which of the following does not form M3+ion?
Due to its small size and high ionization energy boron does not form B3+ ion.
Among the following, ____ is normally found in +2 oxidation state.
Pb is normally found in + 2 oxidation state. Lead (Pb) is found in +2 oxidation state because of maximum inert pair effect.
When vapours of SiCl4 are passed over hot Mg, the product formed is:
SiCl4 + 2Mg → Si + MgCl2
Silicon is an important constituent of
Rocks are mainly silicates.
Producer gas is a mixture of:
Producer gas is a fuel gas and is mixture of CO and N2.
Which of the following is a semiconductor?
Ge is used as a semiconductor in transistors.
Synthesis gas is a mixture of
Mixture of H2 and CO is known as synthesis gas or water gas.
Carborundum is SiC.
____, the allotrope of carbon has the standard enthalpy of formation Δf Ho as zero.
Graphite, the allotrope of carbon has the standard enthalpy of formation Δf H° as zero. The standard enthalpy of formation Δf H° of diamond is 1.98 and the standard enthalpy of formation Δf H° of fullerene is 38.1 kJ mol-1.
____ is known as bone black.
Animal charcoal is known as bone black. Animal charcoal consists of 10% carbon and rest being calcium phosphate.
Which of the following is most stable?
Pb2+ due to inert pair effect.
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