General Science Element, Compound & Mixture

EXERCISE 7.1:

Q1. Define Matter
Ans: Matter is any thing that has mass and occupies space.

Q2. Complete the following concept map.

Q3. How are compound different from elements?
Ans: In elements all the atoms are identical while in compounds basic unit is a molecule. Which is composed of two or more different type of atoms.

EXERCISE 7.2:
1 Ans: No, Hydrogen and oxygen are elements, and elements are the simplest substances.
2 Ans: (a) True    (b) False   (c) True
3.

Elements	Compounds
Sodium+Chlorine	Table salt (NaCl)
Carbon+Oxygen	Carbondioxide (CO2)
Carbon+Hydrogen+Oxygen	Sugar(C12 H22O11)
Sodium+Hydrogent Oxygen+Carbon	Baking Soda (NaHCO3)

4. A mixture possesses the properties of the substances which make up the mixture, For example air is a mixture of many gases such as oxygen, nitrogen, carbondioxide and others, We can change the amount of things in the mixture for example in mixed fruits and nuts we can put more fruits and less nuts.
EXERCISE 7.3:
1.Name these
(a) Element  (b)Mixture   (c) Sublimation  (d) Distillation
2. (a) Crystallization       (b) Sublimation     (c) Distillation  (d)  Decantation   (e) Filtration
(f) Decantation

Additional Questions/Answer

Q1. What is an element?
Ans: Element: An element is a substance, which can not be broken down into two or more parts. Elements are made up of atoms. Carbon, Nitrogen, Sulphur and Iron are some examples of elements.

Q2. What is compound?
Ans: Compound: Compound is a substance that is formed when the atoms of two or more elements combine chemically. A compound contains different kinds of atoms.
For example: A molecule of water (H2O) is made when two hydrogen atoms are combined with one oxygen atom
Hydrogen (Gas)+Oxygen (Gas) à Water (liquid)

Q3. Define mixture.
Ans: Mixture: Mixture is a substance which is made up of two or more substances which are not combined chemically. The substances in a mixture can be solids, Liquids and gases. Example: Air is a mixture of oxygen, nitrogen, carbondioxide and other gases.

Q4. Differentiate between mixture and compound.

Mixture	Compound
1.        Mixture is made up of two or more substances that are not chemically combined, for example air.	Compounds are made up of two or more elements that are chemically combined, for example water.
2.        A mixture possesses the properties of its components.	A compound has properties that are different from its components.
3.        A mixture can be separated into its components by physical methods.	A compound can be broken down into its components by chemical methods only.
4. Components of a mixture are not mixed in a fixed quantity.	Components of a compound are mixed in a fixed quantity.

Q5. How many physical methods are used for separating mixture?
Ans: Some common physical methods for separating mixtures are.
a) Decantation   2) Distillation   3) Crystallization   4) Sublimation
Decantation:
It is a process of removing a liquid from a mixture by pouring it, while leaving the remaining constituents in the container. For example when we cook rice, we simply let the water in the rice decantdown, leaving rice behind.

Distillation:
It is a process of purifying a liquid. When we boil sea water, it turns into steam leaving behind the solid constituents. We can get drinking water from sea water by this method. It is called distilled water.
Crystallization:
The process of cooling a hot saturated solution to obtain solid crystals is called crystallization.
Sublimation:
Some substance undergo a change of state from solid to gas or gas to solid. The conversion of a solid to gas (or vapours) without passing through a liquid phase is called sublimation.
E.g: Phenyl balls sublimate in open air resolve boldness.

Q6. Fill in the blanks.
1). The common states of matter are solid, liquid and gas.
2). Matter is composed of simplest building blocks called atoms.
3). Hydrogen is the simplest element.
4) The most abundant element on the earth is oxygen.
5) The smallest particle of a compound is called molecule.
6) Mercury is a metallic element, which occurs in nature in liquid form.

Posted in: Class-6th,S.Q.A