Physical and Chemical Changes Test - 7

According to this question the correct option will be ‘C’ because The change of milk into curd is both a physical and chemical change. Physical change; as the milk turns into curd and forms a mass as the milk solid make a cluster. And Chemical change; as the lactose in the milk turns into lactic acid and as acid increases the coagulation takes place.

Ice, liquid water and steam are three different states of water, all these are interchangeable depending on the temperature. If ice is heated it changes to liquid water, the process is called melting. If this is cooled back at \(0^{0} C\) ice is formed again, the process is called freezing. liquid water when heated at its boiling point i.e \(100^{\circ} \mathrm{C}\) turns into steam, the process is called boiling.

This steam cools back to the water, the process is called condensation. All of these are physical changes.

Hence, the correct option is (A)

According to this question the correct option will be ‘C’ because the formation of a gas is a clue to chemical changes. The bubbles of gas that you observed form when an antacid is dropped into water is an example of change. Another clue that a chemical change has occurred is the formation of a solid

According to this question the correct option will be ‘C’ because Physical change is a temporary; they are easily reversible. As against this, the chemical change is permanent in nature, i.e. they cannot be reversed, even by reversing conditions. In the physical change, only the form of the substance is changed, but no new product is formed.

If the substance is expanded on melting, the melting point increases when the pressure is increased, because in increased pressure substance try to be in a state where volume decreases.

According to this question the correct option will be ‘C’ because Melting of ice is a physical change because it involves change only in the physical state of water, from ice in the solid state to water in the liquid state. Moreover, no new chemical substance is formed in the process and this change is reversible. Water can be converted back into ice simply by freezing.

According to this question the correct option will be ‘C’ because Aluminum is a metal that is used for many household products, including deck and porch railings, light fixtures and outdoor furniture. Unlike steel, aluminum resists corrosion by moisture and air when exposed to the elements, but salt spray and road salts can cause a condition caused oxidation, which discolors the aluminum surface. A number of methods are used to stop the corroding effects of these salts.

According to this question, the correct option will be ‘D’ because Oxidation-reduction reaction, also called redox reaction, are chemical reactions in which the oxidation number of a participating chemical species changes. The term covers a large and diverse body of processes.

According to this question the correct option will be ‘B’ because Precipitation is not a chemical change, but rather a physical change from one state of matter to another. Precipitation begins as water vapor inside a cloud and then condenses into liquid water, which falls to Earth.

According to this question the correct option will be ‘A’ because When a normal platinum wire is placed over a flame, it glows. This is a physical change because the things that make up the platinum have not been changed, but the appearance has changed.

According to this question the correct option will be ‘B’ because When solid lead nitrate is heated strongly a it turns yellow due to formation of lead oxide and a reddish brown gas is evolved which is nitrogen dioxide. When the evolved gas is passed over wooden glowing splinters it rekindles. This shows the presence of oxygen. Hence the Chemical equation for above reaction is- 2Pb(NO₃)₂ → 2PbO+4NO₂+O₂

According to this question the correct option will be ‘D’ because Salt will only crystallize when you boil off enough water to increase its concentration to about 36% (10 times the concentration of sea water) But if you condense the steam that you create by boiling and concentrating the sea water you will get drinkable water. You cannot crystallize the salt any other way.

According to this question the correct option will be ‘B’ because A change in which one or more new substances are formed is known as chemical change. For Example, when the iron is exposed to air and moisture, rust formation takes place. Rust is nothing but Iron Oxide; a new substance formed out of the reaction.

According to this question the correct option will be ‘B’ because A chemical change results from a chemical reaction, while a physical change is when matter changes forms but not chemical identity. Examples of chemical changes are burning, cooking, rusting, and rotting. Examples of physical changes are boiling, melting, freezing, and shredding. Often, physical changes can be undone, if energy is input.

According to this question the correct option will be ‘A’ because Lime water turns milky when you pass carbon dioxide through it because a reaction that produces a white precipitate takes place. When you pass carbon dioxide through this solution, the two compounds carbon dioxide (CO2) and calcium hydroxide (CaOH2) will react to form white and insoluble calcium carbonate which precipitates out of the solution.