Q. 73.7( 103 Votes )
Which of the following materials fall in the category of a "pure substance"?
(d) Hydrochloric acid
(e) Calcium oxide
A pure substance is made up of only one kind of particles. All the constituent particles of a pure substance are the same in their chemical nature. These particles may be atoms or molecules. All the elements and compounds are pure substances because they contain only one kind of particles. A pure substance cannot be separated into other kinds of matter by any physical process. A pure substance has a fixed composition as well as a fixed melting point and boiling point.
Pure substances are: Ice, Iron, Hydrochloric Acid, Calcium oxide and Mercury. All these substances are pure because these are made of same kind of atoms or molecules. They have fixed melting or boiling points.
On the other hand, Brick, Air, Milk and wood are not pure substances because all of these do not have a fixed composition. Air is a mixture of gases in which the composition of gases is not fixed. Milk is a colloidal solution.
Rate this question :
Two chemical substances X and Y combine together to form a product P which contains both X and Y
X + Y → P
X and Y cannot be broken down into simpler substances by simple chemical reactions. Which of the following statements concerning X, Y and P are correct?
(i) P is a compound
(ii) X and Y are compound
(iii) X and Y are elements
(iv) P has a fixed compositionLakhmir Singh & Manjit Kaur - Chemistry
Two chemical species X and Y combine together to form a product P which contains both X and Y
X + Y → P
X and Y cannot be broken down into simpler substances by simple chemical reactions. Which of the following concerning the species X, Y and P are correct?
(i) P is a compound.
(ii) X and Y are compounds.
(iii) X and Y are elements.
(iv) P has a fixed composition.NCERT Science - Exemplar
Write true or false for the following statements:
A compound is a substance composed of two or more elements, chemically combined with one another in a fixed proportion.Evergreen - Science
Which of the following is a compound?Evergreen - Science
You are given two liquids, one a solution and the other a compound. How will you distinguish the solution from the compound?Lakhmir Singh & Manjit Kaur - Chemistry
Which of the following are compounds?
(i) CO (ii) No
(iii) NO (iv) CoLakhmir Singh & Manjit Kaur - Chemistry
Which of the following materials fall in the category of a “pure substance”?Evergreen - Science
There are three substances X, Y and Z. The substance X does not have a fixed melting point or boiling point and it still shows the individual properties of its constituents. The substance Y is a pure substance which occurs in nature as such. The substance Y has a fixed melting point and boiling point but it cannot be broken down into simpler substances by any chemical means. The substance Z is also a pure substance whose properties are entirely different from those of its constituents. The substance Z can, however, be divided by electrolysis into two substances which belong to the same class of substances as Y.
(a) What type of substance could X be? Name one substance like X.
(b) What type of substance could Y be? Name one substance like Y.
(c) What type of substance could Z be? Name one substance like Z.
(d) Whish process involves absorption or release of an appreciable amount of energy: formation of substance X or formation of substance Z?
(e) Name the three groups into which all the substances like Y are divided on the basis of their properties.Lakhmir Singh & Manjit Kaur - Chemistry
Iron powder and sulphur powder were mixed together and divided into two parts A and B. When part A was heated strongly over a burner, then a substance C was formed. The part B was, however, not heated at all. When dilute hydrochloric acid was added to substance C, then gas D was evolved and when dilute hydrochloric acid was added to part B then gas E was evolved.
(a) What type of substance is B?
(b) What type of substance is C?
(c) Name the gas (i) D, and (ii) E?
(d) Write one characteristic property of gas D.Lakhmir Singh & Manjit Kaur - Chemistry