Lakhmir Singh & Manjit Kaur Test: Is Matter Around Us Pure - Free MCQ

A combination of common salt and Iron filings is a mixture as there is no chemical reaction between them to form new substance.

Mass percent of solution = (mass of solute / mass of solution)×100%(mass of solute / mass of solution)×100%
=     4    ×100%
   4+36
= 10%.

Air is a mixture of gases consisting of approximately 4/5 Nitrogen and 1/5 Oxygen.

A nanometer (nm) is a unit of length in the International System of Units (SI), equal to one billionth of a meter (10^-9 m). It is specifically used to measure very small distances on the nanoscale. Therefore, the correct answer is C, as it accurately describes the nanometer's role as a unit for measuring nano-distance.

At room temperature, Bromine is present in liquid state. Bromine is a non-metal belonging to family of halogens.

The separation of constituents from homogenous mixture is difficult as compared to heterogeneous mixture. Milks is a colloidal substance. So, milk is not a pure substance.

Cesium is a metal which has very low melting point and change into liquid state above  30⁰C.

A dilute solution of alcohol in water is an example of homogenous mixture. Alcohol and water do not forms a separate boundary if left undisturbed and both are uniformly distributed.

B is the correct option.
1.Aerosol particles originating from urban and industrial pollution or smoke from fires have been shown to affect cloud microphysics, cloud reflection of sunlight to space, and the onset of precipitation.
2. a fine dispersion of minute droplets of one liquid in another in which it is not soluble or miscible.
3.Whipped cream is an air-in-water foam in which air cells are surrounded by a film containing fat droplets stabilized by a film of protein. 
4. The use of sol-silicate paint protects the old substrate from further destruction due to UV exposure, and creates an absolutely lightfast and colour-stable surface. 

Air is mixture and no energy change occurs during mixing of air. Cesium and gallium are liquid at room temperature. Pure substance have fixed melting and boiling points. Mixture is not a single substance.

Elements include metals, non-metals and semi-metals (metalloids). Alloys are mixture of two or more elements.

Solution having uniform composition → (A) Homogeneous
Solution with separate boundaries of various components → (C) Heterogeneous
New substances are formed → (B) Chemical change
Melting of ice → (D) Physical change

Adding of common salt (NaCl) to water is physical change as no new substance is formed and no heat is evolved during addition of salt in water.

Metal are generally hard and produce tinkling sound when bent. Non-metals are brittle and compounds cannot be bent.

Solution is a homogeneous mixture because it is made up two or more substance and chemical composition is uniform throughout.
Suspenison is a heterogeneous mixture because the chemical composition is not uniform and particles are arranged differently in a heterogeneous mixture i.e.random arrangement of particles takes place in a heterogeneous mixture.
Solute is the component of a solution that is to dissolved into the solvent.
Solvent is the medium which is in large quantity and solute is in less quantity as it is the matter which is to be dissolved into solvent let's take an example there is sugar and water. You dissolved sugar in water so water here acts as a solvent and sugar here acts as a solute which is to be dissolved into the solvent i.e. present in large quantity.
Thus, the final answer is 1-D, 2-A, 3-C and 4-B.

• The correct answer is:

  a) Milk

  Explanation:

• Milk – It appears uniform, but under a microscope, it has tiny fat globules dispersed in water. This makes it a colloid, which is a type of heterogeneous mixture.
• Salt solution – Salt dissolves completely in water, forming a homogeneous mixture.
• Air – Air is a homogeneous mixture of gases (mainly nitrogen, oxygen, carbon dioxide, etc.).
• Distilled water – Pure substance, not a mixture at all.

Cooking of vegetables is a chemical change because a new substance is formed having new properties and heat is used to change the state. Cooked vegetable cannot be reversed back as raw vegetable.

Mercury is a thick shining liquid used commonly in glass thermometer. It does not stick with wall and expands uniformly on heating.

Cod-liver oil is an example of Emulsion. Emulsion is a kind of colloid in which minute droplets of one liquid are dispersed in another liquid which is not miscible with it.

The solution of Alcohol and water is miscible. Alcohol and water can be separated by the process of fractional distillation due to difference in boiling point of two liquids.

When HCl is added to iron filling then chlorine of HCl reacts with iron by evolving hydrogen gas. The iron dissolves, releasing hydrogen and making an iron chloride solution.

Fe + 2HCl → FeCl₂ + H₂ or

2Fe + 6HCl → 2FeCl₃ + 3H₂

-FeCl₂ is a greenish solution.

The correct option is A.
A thermometer is an instrument that measures temperature. It can measure the temperature of a solid such as food, a liquid such as water, or a gas such as air. The three most common units of measurement for temperature are Celsius, Fahrenheit, and kelvin. The Celsius scale is part of the metric system.

In the homogeneous mixture, two or more than two components have same composition and properties throughout the mixture