Q1: Name the process by which pure copper sulphate can be obtained from its impure sample.
Ans: Crystallisation is the process used to obtain pure copper sulphate from an impure sample.
Q2: What is a homogeneous mixture of two or more substances called?
Ans: A solution is a homogeneous mixture in which the solute is uniformly distributed in the solvent, so the composition is the same throughout.
Q3: What is the component of a solution that is present in a smaller proportion called?
Ans: The solute is the component of a solution that is present in a smaller proportion and is dissolved by the solvent.
Q4: Naphthalene and sand can be separated by the process of
Ans: The separation of naphthalene from sand can be achieved through the process of sublimation, because naphthalene changes directly from solid to vapour on heating while sand does not.
Q5: What is an element made up of?
Ans: An element is made up of only one type of atom; for example, carbon (C) and iron (Fe) each consist of only one kind of atom.
Q6: What type of mixture is Milk of Magnesia?
Ans: Milk of Magnesia is a suspension, not a true solution; it contains fine solid particles dispersed in a liquid which may settle on standing.
Q7: Give two examples of colloids from your daily life.
Ans: Examples of colloids are milk (liquid dispersed in liquid) and fog (tiny liquid droplets dispersed in air).
Q8: Name the constituents of German silver.
Ans: German silver is an alloy made of copper, zinc, and nickel.
Q9: What is the meaning of the ‘concentration of a solution’?
Ans: Concentration of a solution is the amount of solute dissolved in a specified amount of solvent or solution; a greater amount of dissolved solute means a higher concentration.
Q10: Name the process used to separate liquids which have a difference in boiling points of less than 25°C.
Ans: Fractional distillation is used to separate such liquids; it employs a fractionating column to separate components with close boiling points.
Q11: Name two categories of pure substances.
Ans: The two categories of pure substances are an element and a compound.
Q12: Define the term Solvent.
Ans: A solvent is the component of a solution present in larger amount that dissolves the solute to form the solution.
Q13: What are two types of matter on the basis of composition?
Ans: Pure substances and mixtures are the two main types of matter based on composition.
Q14: Name the types of mixtures.
Ans: The two types of mixtures are homogeneous mixtures (uniform composition) and heterogeneous mixtures (non-uniform composition).
Q15: Give natural examples of a mixture.
Ans: Examples of natural mixtures include seawater, mineral ores and soil, all of which contain a variety of substances combined together.
Q16: Name a metal that is liquid at room temperature.
Ans: Mercury is the only metal that is liquid at ordinary room temperature.
Q17: What is the principle of separation?
Ans: The principle of separation is based on differences in physical or chemical properties of components, such as boiling point, solubility, particle size or magnetic properties, and using these differences to separate them.
Q18: Give an example of a liquid and a liquid-type solution.
Ans: Vinegar is a liquid solution made of acetic acid dissolved in water.
Q19: Define dispersion medium.
Ans: The dispersion medium is the component present in excess in a colloid that acts as the medium in which the colloidal particles are dispersed.
Q20: Define the term heterogeneous mixture.
Ans: A heterogeneous mixture is one in which the components are not uniformly distributed and different parts of the mixture show different properties.