Science M.C.Q

Element B has the electronic configuration of 2, 6. It requires 2 electrons to complete its octet. On the other hand, element D has the electronic configuration of 2, 8, 2. It requires to release 2 electrons to complete its octet.
Thus, both atoms react to form ionic bonds by transfer of electrons.

Bromine is the non-metal that is a liquid.

Atomic number of helium is 2. It contains 2 electrons in its atom.

Stainless steel is an alloy of iron, chromium and nickel. It is extremely strong and tough and does not corrode at all.

Cinnabar is an important ore of mercury. Its compound is mercury (II) sulphide (HgS).

Compound Z is an ionic compound formed by transfer of electrons. Ionic compounds have high melting points.

Both mercury and copper are less reactive metals and are placed low in the reactivity series. Hence, they can be extracted by heating their sulphides in air and further reducing their oxides by heating.

In an oxygen molecule, each oxygen atom shares its 2 electrons to complete its octet and forms double covalent bond between them.

Mercury is a low reactive metal. Thus, it can be extracted from its ore cinnabar, HgS, by heating it in air.

Rock salt is a chloride ore of sodium. The name of the compound in the ore is sodium chloride with chemical formula NaCl.

Because lithium ion is a good conductor of electricity.

Calcium is the metal that can react with water to form calcium hydroxide, which is basic in nature. Hence it turns phenolphthalein solution pink.

Potassium and magnesium are metals whose oxides are basic in nature. These oxides turn red litmus solution to blue.

Element Y has 1 less electron to complete its octet which is a property of non-metals. On the other hand, element ​Z has 2 extra electrons to become stabilised which is a property of metals.

Generally, alloys containing mercury as one of its constituents are known as amalgam. Zinc amalgam is an alloy of zinc and liquid mercury.

Gold (Au) and silver (Ag) are highly non-reactive. Hence, they are available in native state in nature and do not react with oxygen or any other element in the atmosphere.

Phosphorus and sulphur are non-metals whose oxides are acidic in nature. These oxides turn blue litmus solution to red.

An ethyne molecule (H - C ≡ C - H) contains a triple bond between two carbon atoms and two single bonds between carbon and hydrogen atoms.

Zinc oxide can react with both acids and bases to form salt and water.

Sulphide ores are transformed into oxides by the process of roasting. In this process, concentrated ore is heated in the presence of surplus air. Example: Zinc blende, ZnS, a sulphide ore of zinc, is roasted in the presence of air. On roasting​, zinc sulphide gets transformed into zinc oxide.

Because ionic compounds conduct electricity only in molten state or when dissolved in water to form aqueous solution.

Ag will be replaced from the solution of its salt by the other three metals.

An amalgam is an alloy of mercury with one or more metals. The combination of sodium with liquid mercury is called sodium amalgam. Amalgam of mercury with gold, silver or zinc is widely used for dental fillings.

Both aluminium and zinc oxides react with acids and bases to form salt and water.

Brass is an alloy of copper and zinc. It comprises of 80 percent copper and 20 percent zinc.

Both these compounds are formed by sharing of electrons and hence, they form covalent bonds and not ionic bonds.

Galvanisation is a process that involves dipping of iron objects into melted zinc. This gives a thin coating of zinc layer on the iron object that protects it from corrosion. Zinc, being a highly reactive metal, forms a thin layer of zinc oxide, which prevents iron from getting exposed to the atmospheric air.

Because it is a covalent compound.

An amalgam is an alloy of mercury with one or more metals. The combination of sodium with liquid mercury is called sodium amalgam. Amalgam of mercury with gold, silver or zinc is widely used for dental fillings.

This is because magnesium and aluminium are highly reactive metals and are placed high in the reactivity series. This is also due to the fact that their oxides are very stable and cannot be reduced easily.

Mercury (Hg) is the metal that exists in liquid state at room temperature.

Na is soft and can be cut with a knife. It is very reactive and cannot be kept in open air. It reacts vigorously with water.

Zinc blende (zinc sulphide or ZnS) is a sulphide ore of zinc. Sulphide ores are converted to metal oxides by roasting (heating in the presence of air). When zinc blende is heated in the presence of surplus air, it is converted into zinc oxide.

Helium is the only noble gas that has 2 electrons in its valence shell. Other noble gases have 8 electrons in their valence shells.

Element P needs 4 electrons to complete its octet. They can be shared with element S, which needs only 1 electron to complete its octet.