Important Questions: Materials: Metals And Non Metals
20 Questions MCQ Test Science Class 8 | Important Questions: Materials: Metals And Non Metals
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Potassium is more reactive than Sodium and Lithium because Potassium is bigger than them. So outermost electron is farther away from nucleus. So the ionization energy in K is less than that in Na or in Li. So Potassium is more reactive than many other metals.
The liquid metal at room temperature is:
The correct option is A.
Liquid metal consists of alloys with very low melting points which form a eutectic that is liquid at room temperature. The standard metal used to be mercury, but gallium-based alloys, which are lower both in their vapor pressure at room temperature and toxicity, are being used as a replacement in various applications.
The metal which is stored in kerosene:
The non-metal which is liquid at room temperature is:
Metals that are liquids at room temperature are mercury (Hg) and gallium (Ga).
Non-metals liquid at room temperature - bromine (Br).
However, other elements such as caesium (Cs), rubidium (Rb) and francium (Fr) also become liquids at a few degrees above room temperature.
Materials around us can be classified into
All metals are solids except
The metal which can be cut with a knife
Sodium and potassium are soft metals. So an ordinary knife and a little pressure is enough to cut them.
What happens when Non-Metals react with water?
The property of metals by which they can be beaten in to thin sheets is called-
Non-metal can be converted into wires.
Non- metals are non - (malleable and ductile). They are very brittle, and cannot be rolled into wires or poundes into sheets.
Bromine is only a liquid metal.
The correct option is B.
bromine is a fairly abundant element but has a rare property: it is the only nonmetal to exist in liquid form at room temperature, and one of only two elements (the other being mercury) that is liquid at room temperature and pressure.
The property of beating metals into thin sheets is called malleability.
Metals produce basic oxide with oxygen.
The correct option is A.
Oxides of metals are actually basic in nature not alkaline. This can be explained as oxygen reacts with metal to form corresponding metal oxides which are basic in nature. Also these metal oxides react with acid to form salt and water this shows that they are basic in nature.
Metals are solid except mercury.
Non‑metals are found in all the three states like solid, liquid, gas.
True, because there are some non metals that are found in solid, liquid and gas. diamond is found in solid state form, bromine found in liquid state form and helium and oxygen are found in gas state.
Sodium and potassium are kept in water.
Sodium and potassium metals reacts very vigorously with water ; this reaction gives out so much heat that the hydrogen evolved catches fire. Therefore, these metals are stored under kerosene .
So, the given statement is false.
Sodium is such a hard metal that it cannot be cut with a knife.
Sodium is a soft metal that can be cut easily with a table knife. It is not a hard metal. Freshly cut sodium metal has a bright, shiny surface that quickly becomes a dull gray as it reacts with oxygen in the air around it.
So, the given statement is false.
Chlorine is a very reactive metal.
The chlorine is a very reactive now metal. All noble gases are considered as non - metals.
So, the given statement that chlorine is a very reactive metal, is false.
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