Science Test Form

Oxygen is the correct answer because it is a highly reactive gas that supports combustion. When a wooden splinter is exposed to oxygen, it reacts with the oxygen molecules in the air, resulting in a chemical reaction known as combustion. This reaction releases energy in the form of heat and light, causing the wooden splinter to glow. Therefore, oxygen is responsible for igniting the glowing wooden splinter.

The correct answer is electric -> heat because an electric kettle converts electrical energy into heat energy to boil water.

The correct answer is "right" because the percentage of oxygen present in the air is indeed 21 percent. This is a well-known fact and is supported by scientific data. Oxygen is a vital component of the Earth's atmosphere and is necessary for the survival of many organisms, including humans.

During photosynthesis, green plants use sunlight, water, and carbon dioxide to produce glucose (a form of sugar) and oxygen. The oxygen is released into the atmosphere as a byproduct of the process. This oxygen is essential for the survival of many organisms, including humans, as it is needed for respiration. Therefore, the correct answer is oxygen.

When carbon dioxide gas is added to lime water, a chemical reaction occurs. This reaction forms calcium carbonate, which is insoluble and appears as a cloudy precipitate in the solution. Therefore, the presence of carbon dioxide causes lime water to turn cloudy.

The energy that causes water to evaporate and form clouds is heat energy. Heat energy increases the temperature of water, causing the water molecules to gain energy and become more active. As a result, some of the water molecules at the surface gain enough energy to break the bonds holding them together and escape into the air as water vapor. These water vapor molecules then rise and cool, forming clouds. Therefore, heat energy is responsible for the process of evaporation and cloud formation.

The correct answer is "stronger immunity system" because air pollution does not have a positive effect on the immune system. In fact, air pollution can weaken the immune system and make individuals more susceptible to respiratory infections and diseases.

Carbon dioxide is an acidic gas because when it dissolves in water, it forms carbonic acid (H2CO3). This acid can release hydrogen ions (H+) into the solution, making it acidic. Carbon dioxide is also known to lower the pH of water when dissolved, which further supports its acidic nature.

A glowing wooden splinter is used to identify oxygen because oxygen supports combustion. When a wooden splinter is brought near oxygen, it ignites and continues to burn brightly. This is due to the fact that oxygen is a highly reactive gas that readily supports the combustion process. Therefore, by observing if a wooden splinter ignites or not, we can determine the presence of oxygen.

Oxygen is considered a chemical element because it is a pure substance that cannot be broken down into simpler substances by chemical means. It is also a gas at room temperature and normal atmospheric pressure, making it a gas.