Physics Chemistry & Biology Test _ Chemical Reactions and Equations
Which type of reaction is natural gas combustion an example of?
  • Endothermic
  • Exothermic
  • Addition
  • Decomposition
Explanation:

Natural gas combustion is an example of an exothermic reaction. In an exothermic reaction, energy is released in the form of heat. When natural gas (primarily methane, CH₄) burns, it reacts with oxygen (O₂) to produce carbon dioxide (CO₂) and water (H₂O), and releases heat energy:

CH4​+2O2​→CO2​+2H2​O+heat

The release of heat during the combustion process characterizes it as an exothermic reaction.

The white powder produced when a magnesium ribbon is burnt in the air is —
  • Magnesium carbonate.
  • Magnesium nitrate.
  • Magnesium oxide.
  • Magnesium hydroxide.
Explanation: When magnesium ribbon is burned in the air, it reacts with oxygen to form magnesium oxide. The white powder produced is magnesium oxide (MgO). The reaction can be represented as: 2Mg+O2(oxygen)→2MgO
An example of which of the following reactions is the reaction that produces burnt lime by heating lime-
  • Addition
  • Subtraction
  • Abduction
  • Taapsee
What color of skin falls on the surface of the copper material when the copper corrosion occurs?
  • Black
  • Brown
  • Green
  • Red
Explanation:

When copper corrodes, it forms a green patina on its surface due to the formation of copper carbonate and copper chloride.

This green color is commonly seen on weathered copper surfaces, such as those on old copper roofs and statues.

What color of skin on the surface of the silver is caused by the erosion of the silver?
  • Black
  • Green
  • Brown
  • Motia
Explanation: The black coloration on the surface of silver due to erosion is typically caused by the formation of silver sulfide (Ag₂S) as a result of silver reacting with sulfur compounds in the air. This reaction leads to tarnishing, which appears as a black layer on silver items.
The basis for verifying a jumping equation is-
  • Law of conservation of energy
  • Rules of fixation
  • The law of mass
  • None of the above.
Explanation: The basis for verifying a jumping equation is the law of conservation of energy, not the law of mass. This principle states that energy cannot be created or destroyed, only transformed. During a jump, chemical energy from muscles converts into kinetic energy as a person leaves the ground, and then into gravitational potential energy as they rise. At the apex, kinetic energy is minimal and potential energy is maximal. As the person descends, potential energy converts back into kinetic energy. Thus, energy transformations during a jump are explained by the law of conservation of energy, ensuring that total mechanical energy remains constant.
When pieces of zinc are dropped into copper sulphate solution, zinc sulphate and copper are produced. This reaction is an example of which of the following reactions–
  • Removal
    • Explanation:

    The reaction you described, where zinc pieces are added to copper sulfate solution producing zinc sulfate and copper, is an example of a single displacement reaction.

    Here's the reaction in detail: 

    Zn (s)+CuSO4​(aq)→ZnSO4​(aq)+Cu (s)

    In a single displacement reaction, one element replaces another in a compound.

    The options you provided are:

    (a) Removal
    (b) Subduction
    (c) Double removal
    (d) Addition

    None of these options directly correspond to the correct term, which is "single displacement reaction." However, if you must choose from the given options, none accurately describe the reaction. The most closely related term would be "removal" (a), though it is not a standard term for this type of reaction.