Matter In Our Surrounding 9th Class

Explanation
The correct answer is "mass/volume". Density is defined as the mass of an object divided by its volume. It represents how much mass is packed into a given volume. Therefore, the correct formula to calculate density is mass divided by volume.

Explanation
Density is a measure of how much mass is contained in a given volume. It is calculated by dividing the mass of an object by its volume. The unit for density is kilograms per cubic meter (kg/m³), which represents the amount of mass in kilograms that is present in each cubic meter of space. Therefore, the correct answer is kg per cubic meter.

Explanation
Mercury is a metal that is liquid at room temperature. Unlike most other metals, which are solid at room temperature, mercury has a low melting point of -38.83 degrees Celsius (-37.89 degrees Fahrenheit). This unique property is due to the weak metallic bonding between its atoms, allowing them to move more freely and giving mercury its liquid state.

Explanation
Lead has the highest density among the given options. Density is defined as the mass of a substance per unit volume. Lead is a dense metal with a high atomic mass, which contributes to its high density. Water, kerosene oil, and iron have lower densities compared to lead.

Explanation
Gases have the highest rate of diffusion among all the three states of matter because their particles are in constant random motion and are far apart from each other. This allows them to spread out and mix with other gases more easily compared to liquids or solids. In liquids, the particles are closer together and in constant motion, but not as fast as in gases. Solids have the slowest rate of diffusion because their particles are tightly packed and have limited mobility. Therefore, the statement is true.

Explanation
Option 1 is a homogeneous mixture because it consists of a single phase and its components are uniformly distributed throughout. This means that the composition of Option 1 is the same throughout the entire sample. In contrast, Option 2 may be a heterogeneous mixture because it could contain multiple phases and its components may not be evenly distributed. Therefore, Option 1 is the correct answer as it meets the criteria for a homogeneous mixture.

Explanation
To convert Kelvin to Celsius, we need to subtract 273 from the given value. In this case, 273 Kelvin minus 273 equals 0 Celsius. Therefore, the approximate Celsius value for 273 Kelvin is 0.