Advertisements
Advertisements
प्रश्न
Define a compound. Give two points of evidence to show that sodium chloride is a compound.
Advertisements
उत्तर
A compound is a substance made up of two or more elements combined together chemically in a fixed proportion by mass.
Sodium chloride (NaCl) is a compound because:
- It is made up of two elements, sodium and chlorine, and the nature of NaCl is completely different from its constituent elements.
- Sodium and chlorine are present in a fixed proportion in sodium chloride.
APPEARS IN
संबंधित प्रश्न
Intermolecular space is maximum in .......... less in ............ and the least in .........
Solids have definite shape and definite volume.
Name the terms for the change of a solid into liquid.
What are molecules ?
Which of the following materials fall in the category of a “pure substance”?
- Ice
- Milk
- Iron
- Hydrochloric Acid
- Calcium oxide
- Mercury
- Brick
- Wood
- Air
Give reason why copper metal is used for making electric wires.
State one property in which a solution of sugar in water resembles a mixture of sugar and sand, and one property in which it differs from it.
Name a metal which has a low melting point.
Which of the following are not compounds ?
Chlorine gas, Potassium chloride, Iron powder, Iron sulphide, Aluminium foil, Iodine vapour, Graphite, Carbon monoxide, Sulphur powder, Diamond
Calculate the concentration of a solution which contains 2.5 g of salt dissolved in 50 g of water.
State whether the following statement is true or false :
Bread is an example of solid foam.
When the solid A is added to water, it dissolves with the evolution of a lot of heat and making little explosions to form two products B and C. The properties of products B and C are entirely different from those of solid A as well as water. Moreover, products B and C cannot be reconverted into solid A and water. When another solid D is added to water, it dissolves with the absorption of a little heat to form a product E which cools down. The product E shows the properties of both, solid D as well as water. Moreover, product E can be converted into solid D and water.
(a) What type of change occurs when solid A is dissolved in water ? Why ?
(b) What type of change occurs when solid D is dissolved in water ? Why ?
(c) Name a metal which you think could behave like solid A. Also name the products B and C.
(d) Name the solid D if it is the one which is used in making ordinary dry cells.
(e) Name the process by which D can be recovered from E.
Pure copper sulphate can be obtained from an impure sample by the process of :
Which among the following ______ will get attracted to by magnet?
Name the metals that are used in jewellery.
A standard sheet of paper is about ______ of atoms thick
Which among the following is not a matter?
Solids possess very high kinetic energy.
Write scientific reason.
Lemon sherbat has sweet, sour and salty taste and it can be poured in a glass.
Define the term matter.
