Physical and Chemical Changes Test - 9

According to this question the correct option will be ‘B’  because Stainless steel is an alloy of Iron with a minimum of 10.5% Chromium. Chromium produces a thin layer of oxide on the surface of the steel known as the 'passive layer'. This prevents any further corrosion of the surface.

A reversible process is the one which is carried out infinitely slowly through a series of steps so that the system and the surroundings always remain almost in equilibrium state.

In case of Isothermal compression, temperature of the system is kept constant whereas its volume is decreased.

∵ The system can be brought back to its initial state without leaving any effect on the surroundings. Thus, it is reversible.

According to this question the correct option will be ‘a’  because  Turning on light bulb does not lead to a chemical change. The physical process leading to “light “ production is caused by resistance of the filament in the bulb converting electrical energy to light and heat.

According to this question the correct option will be ‘A’  because eruption of volcano is a chemical change. is it true or false. It is generally considered as a physical change however some of the reactions of metals or minerals present in the volcano can react chemically but instead the whole volcano eruption is a physical change.

According to this question the correct option will be ‘B’ because Sugar dissolving in water is a physical change and not a chemical one. Chemical changes only occur when new substances form. Dissolving sugar in water does not cause a chemical reaction to take place.

According to this question the correct option will be ‘B’  because Mixing of ash obtained by the burning of magnesium with water is a chemical change. When magnesium is burnt in air, it forms magnesium oxide in the form of white ash. Magnesium (Mg)+ Oxygen (O 2) → Magnesium oxide (MgO) When magnesium oxide dissolves in water, it forms a new substance, magnesium hydroxide.

According to this question the correct option will be ‘A’  because  The digestion processes involve changing the composition of materials (food) by chemical interactions – changes in bonding, oxidation states and structure – of the materials with other chemicals (enzymes, acids) in our digestive tracts. For comparison, a purely “physical change” does not change the composition of a material.

According to this question the correct option will be ‘A’ because The formula of acetic acid is CH3COOH and the formula of sodium hydrogen carbonate is NAHCO3. When they are mixed they react and produce carbon dioxide gas that erupts out as bubbles from the solution producing water also.

If new substance are formed, the molecular arrangement of the compound has changed and hence the process is irreversible.

∴  it is a chemical change.

According to this question, the correct option will be ‘A’ because Beating aluminum to make Aluminum foil is a physical change because, with the beating, molding, heat pressing and fabrication process, people can develop their products or aluminum foils with the aluminum sheets. Here no chemical changes are seen and you can find some physical improvement in this fabrication process.

Since, a chemical reaction takes place when a compound is formed, it is a chemical change accompanied with change in energy.

All of the following changes are irreversible because we can not convert the product into reactant again.

1) Milk to paneer.

2) Cow dung to biogas.

3) Grain to its flour.

According to this question the correct option will be ‘A’  because burning of coal is a chemical change hence it is permanent change.

According to this question the correct option will be ‘D’ as 

Methods used to prevent Rusting of Iron are as follows: 

• Alloying – Since Rusting of Iron is a chemical process that happens because

• Galvanizing – Galvanizing a metal object means to coat the surface of that object with a layer

• Coating and Painting – Coating the surface of a metal object with a layer.

The germination of a seed is a slow and irreversible process as it takes few days to months to germinate a seedling from a seed, and this is irreversible because the same seedling which grows into a plant cannot revert back in its growth.

The growth of seedlings in a crop is a desirable change i.e the changes which are beneficial to nature or which does not cause any harm to nature.

And this is a chemical change as it involves many hormones and enzyme actions.