Ques: Q: What form does formaldehyde take at room temperature? Read this paragraph and choose the correct option from the provided answers: Formaldehyde is a gas at room temperature. Acetaldehyde boils at 20C; in an open vessel, it boils away in a warm room. Most other common aldehydes are liquids at room temperature. Choices: - solid - liquids - plasma - gas A:
Ans: gas

Ques: Q: What is a combination of two or more substances in any proportions called? Read this paragraph and choose the correct option from the provided answers: A mixture is a combination of two or more substances in any proportions. The substances in a mixture do not combine chemically, so they retain their physical properties. Choices: - Combination - structure - mix - mixture A:
Ans: mixture

Ques: Q: Where does most of the earth's energy come from? Read this paragraph and choose the correct option from the provided answers: Give an example of how matter cycles. While matter cycles round and round in the Earth System, ENERGY FLOWS through the Earth System. The vast majority of Earth's energy comes from the sun, flows into the Earth's System, and flows out of the Earth's System into space. If all the energy that comes to Earth from the sun were to stay on Earth, the Earth would melt away. But the energy that comes to Earth from the sun does not stay. Eventually it radiates back out to space as heat. We know this because the average temperature of the Earth has remained relatively constant. If the energy from the sun were to stay on Earth, the Earth's average temperature would rise. Some of the sun's energy is reflected by the atmosphere, some is absorbed by the Earth and re-radiated as heat, some evaporates water and powers the water cycle, some is captured by plants and used to make sugars, and some powers the wind but eventually ALL of the energy that comes to the Earth from the sun leaves the Earth and flows into space. For this reason we say that energy flows through the Earth System. Choices: - magnetic field - its core - its atmosphere - sun A:
Ans: sun

Ques: Q: How does litmus paper indicate the ph value of a solution? Read this paragraph and choose the correct option from the provided answers: There are two common ways to measure pH. When only an approximate pH value is needed, an inexpensive test involves the use of acid-base indicators , which change color based on the relative acidity of the solution. One type of common indicator is litmus paper. For example, if a piece of litmus paper is dipped into an acidic solution (pH below ~4.5), it will turn red, and dipping it into a basic solution (pH above ~8.5) will turn it blue. Solutions of intermediate pH will result in various shades of purple. Because different indicators change color at different pH values, the use of multiple indicators can generally narrow down the possible pH of a solution to a range of about 0.5-1 pH units. Figure below shows the colors exhibited by various indicators at different pH values. Choices: - by texture - by shape - by smell - by color A:
Ans:
by color