Class 9 NCERT Science Quiz

Methane Molecule

• Methane (CH4) has a tetrahedral shape with bond angles of approximately 109.5 degrees.
• This geometry arises from four hydrogen atoms symmetrically bonded to a central carbon atom.

Gravitational Force

• The SI unit of gravitational force is the newton (N).
• One newton is defined as the force required to accelerate a one-kilogram mass by one meter per second squared.

Law of Conservation of Mass

• The Law of Conservation of Mass was proposed by Antoine Lavoisier.
• It states that mass is neither created nor destroyed in chemical reactions, leading to the conclusion that the mass of reactants equals the mass of products.

Molecular Mass of Carbon Dioxide

• The molecular mass of carbon dioxide (CO2) is approximately 44.01 g/mol.
• This is calculated by adding the atomic masses of one carbon atom (about 12.01 g/mol) and two oxygen atoms (approximately 16.00 g/mol each).

Dalton's Atomic Theory

• A statement that is not a postulate of Dalton's atomic theory includes the modern understanding of subatomic particles and the existence of isotopes.
• Dalton’s theory originally proposed that atoms are indivisible and identical in mass and properties for a given element.

Universal Gravitational Constant

• The value of the universal gravitational constant (G) is approximately 6.674 × 10^-11 N(m/kg)².
• It is a key component in Newton's law of universal gravitation, relating the force between two masses and the distance separating them.

Test your knowledge of Class 9 NCERT topics "Atom and Molecules" and "Gravitation" with this quiz. Answer questions about the shape of a methane molecule, the SI unit of gravitational force, and the scientist who proposed the Law of Conservation of Mass. See how well you remember these important concepts from your science class.