Melting And Freezing Quiz Questions And Answers

Explanation
Water is considered to be very dynamic because it can exist in three different states: solid (ice), liquid (water), and gas (water vapor). It can easily change from one state to another depending on the temperature and pressure conditions. Additionally, water is constantly moving and flowing, whether it is in the form of rivers, oceans, or even in the atmosphere as clouds. This dynamic nature of water is essential for various natural processes and plays a crucial role in shaping the Earth's surface and supporting life.

Explanation
When ice is exposed to heat, it absorbs the thermal energy, causing the ice molecules to gain energy and vibrate more rapidly. This increase in molecular motion disrupts the rigid structure of the ice, causing it to break down and melt into liquid water. Therefore, heat is the primary cause of ice melting.

Explanation
The boiling point of water in the Kelvin scale is 373K. This is because the Kelvin scale starts at absolute zero, which is the lowest possible temperature. The boiling point of water is the temperature at which it changes from a liquid to a gas, and in the Kelvin scale, this occurs at 373K.

Explanation
The explanation for the given correct answer is that the process of changing water to ice or liquid is indeed called a change of state of matter. When water freezes, it undergoes a change of state from a liquid to a solid, forming ice. Similarly, when ice melts, it undergoes a change of state from a solid to a liquid, becoming water again. These changes in state are a fundamental concept in the study of matter and its properties.

Explanation
Molecules stay the same despite changes in the state of matter. In different states of matter (solid, liquid, gas), the arrangement and movement of molecules may change, but the actual molecules themselves remain the same. The number and type of molecules do not change when matter undergoes a phase transition, only their arrangement and energy. Therefore, molecules are the constant factor regardless of the state of matter.

Explanation
Water (H2O) consists of two hydrogen atoms bonded to one oxygen atom. Therefore, there are two hydrogen atoms in water.

Explanation
Hydrogen can form hydrogen bonds with electronegative atoms like nitrogen and oxygen. Potassium, on the other hand, is a metal and does not form hydrogen bonds. Therefore, the correct answer is oxygen, as hydrogen can form hydrogen bonds with oxygen atoms.

Explanation
The atomic number of oxygen is 8. It is not listed as any of the options given (Two, Three, Five, None of the above).

Explanation
Oxygen typically has a charge of negative due to its high electronegativity and tendency to gain electrons in chemical reactions. However, the given answer is incorrect as it states that oxygen has a positive charge.

Explanation
The melting point of ice is 0°C. This is the temperature at which ice changes from a solid state to a liquid state. At this temperature, the ice absorbs enough heat energy to break the hydrogen bonds between its water molecules and transitions into liquid water. Therefore, 0°C is the correct answer for the melting point of ice.