Explanation

• Carbon Dioxide (CO2) is a greenhouse gas that traps heat in the Earth's atmosphere.
• It contributing to the greenhouse effect and global warming.

Explanation

• Crystallization is the process of separating a soluble solid from a solution by allowing the solution to cool and form crystals.
• This process is used to purify substances and obtain a solid in a pure form.

Explanation

• Solar power is a renewable energy source that generates electricity from sunlight.
• It does not emit carbon dioxide (CO2) or any other greenhouse gases.

The sources of carbon dioxide emissions:

• Burning of fossil fuels (such as coal, oil, and natural gas) releases CO2 into the atmosphere.
• Burning wood (such as in fireplaces or woodstoves) also releases CO2.
• Respiration (the process by which living organisms breathe) releases CO2 as a byproduct.
• Car exhaust smoke (from internal combustion engines) contains CO2, as well as other pollutants.

Explanation

• Photosynthesis is the process by which plants, algae, and some bacteria.
• It convert light energy from the sun into chemical energy in the form of glucose (sugar), using carbon dioxide and water as reactants.

Explanation

• Magnesium (Mg) is an element, not a compound.
• It is a pure substance made up of only one type of atom.
• Whereas compounds are made up of two or more different elements.

Examples of compounds:

• Water (H2O) - Compound of Hydrogen and Oxygen
• Common salt (NaCl) - Compound of Sodium and Chlorine
• Washing soda (Na2CO3) - Compound of Sodium, Carbon, and Oxygen
• Carbon dioxide (CO2) - Compound of Carbon and Oxygen
  
• Sugar (C6H12O6) - Compound of Carbon, Hydrogen, and Oxygen

Explanation

The incorrect statement is: Metals are dull and soft.

Metals are typically:

• Solid at room temperature
• Have high melting and boiling points
• Good conductors of heat and electricity
• Shiny (although some metals may have a dull appearance due to oxidation or other surface treatments)
• Ductile (can be drawn into thin wires or sheets)
• Malleable (can be pounded into shape without breaking)

Explanation

• The lightest gas used for filling party and advertisement balloons is hydrogen.
• However, due to its flammability, helium is more commonly used despite being slightly heavier, because it is safe and non-reactive.

Explanation

• Air is a mixture of different gases.
• Primarily consisting of nitrogen (78%), oxygen (21%), and trace amounts of other gases.

Explanation

• Sand does not dissolve in water.
• Unlike sugar, glucose, and salt, which are all soluble in water.

Explanation

Aluminum is the most abundant metal in the Earth's crust, and the third most abundant element therein, after oxygen and silicon.

MOST IMPORTANT KEY POINTS:

Most abundant elements found in air are? (1) Nitrogen (2) Oxygen (3) Argon

Most abundant elements found in earth’s crust are? (1) Oxygen (2) Silicon (3) Aluminum

Most abundant elements found in Universe are? (1) Hydrogen (2) Helium (3) Oxygen

Most abundant elements found in Human Body are? (1) Oxygen (2) Carbon (3) Hydrogen