Chemistry · Some Basic Concepts Of Chemistry · NEET
| Definition | Amount of matter in an object | Gravitational force on that mass |
| Depends on gravity? | No, constant everywhere | Yes, changes with location |
| SI unit | Kilogram (kg) | Newton (N) |
| Type of quantity | Scalar (only size) | Vector / force (size + downward direction) |
| Formula | Fixed property (counts matter) | Weight = mass x g |
| Measured by | Beam / analytical balance | Spring balance |
| On the Moon (g about 1/6) | Same as on Earth | Becomes about 1/6 |
No, they are different in physics. Mass is the amount of matter in an object and is measured in kilograms (kg). Weight is the force of gravity acting on that mass and is measured in newtons (N). In daily life people say 'my weight is 60 kg', but scientifically that 60 kg is your mass. Your true weight would be about 588 N (mass x g = 60 x 9.8). For NEET, always treat mass and weight as two separate ideas.
Mass depends only on how much matter (how many atoms) an object contains, and that number does not change when you move it. Weight = mass x g, where g is the acceleration due to gravity. When you go to the Moon, g becomes about 1/6 of Earth's value, so your weight becomes 1/6, but your mass is exactly the same because you still have the same atoms.
Kilogram (kg) is the SI unit of MASS, not weight. NCERT clearly states the SI unit of mass is the kilogram. The SI unit of weight is the newton (N) because weight is a force. So writing 'weight = 5 kg' is technically wrong; correct forms are 'mass = 5 kg' or 'weight = 49 N'. NEET can trap you on this exact point.
The Moon's gravity is about 1/6 of Earth's. Weight = mass x g. On the Moon g is smaller, so the gravity pull (weight) is smaller. But mass counts the matter in your body, and you still have every atom you started with, so mass does not change. This is the single most common way NEET tests this concept.
No. Mass is independent of gravity, location, temperature, or pressure. It is a fixed property of the object. Only weight depends on gravity because weight = mass x g. So in space (zero gravity), an astronaut's weight is nearly zero but their mass is unchanged.
A common beam or analytical balance (the type NCERT shows in the lab) compares your object against standard masses, so it actually measures MASS and gives the same reading anywhere. A spring balance (bathroom scale type) measures the pulling force, which is WEIGHT, so its reading would change on the Moon. This subtle point can appear in NEET assertion-reason questions.
Weight is a FORCE (the gravitational force on an object), so it has both size and direction (always pointing down, toward the centre of the Earth). Mass is a scalar quantity with only size. This is why weight is measured in newtons and mass in kilograms.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
The SI unit of mass is the kilogram (kg). The SI unit of weight is the newton (N), because weight is a force equal to mass times the acceleration due to gravity (g).
Mass is the amount of matter in an object and stays constant everywhere; weight is the gravitational force on that mass and changes with location (for example, it is 1/6 on the Moon).
No, any object made of matter has some mass. But its weight can be nearly zero, for example in deep space where gravity is almost absent, because weight = mass x g and g is near zero there.
Because chemistry measurements rely on mass (in kg or g). Chemists always use mass, not weight, since mass is fixed and reproducible in any lab worldwide. Understanding this keeps your unit work correct in mole and stoichiometry questions.
Scientifically, 60 kg is your mass. Your weight in that case is about 588 N on Earth (60 x 9.8). People just call mass 'weight' in everyday speech.
