Which term describes the variable that remains the same in each and every trial?

• A. Constant
• B. Isotonic
• C. Polarity
• D. Adhesion

Answer: (A)

The main idea is that a constant is a factor kept the same in every trial. Keeping certain variables unchanged allows you to isolate the effect of the factor you’re testing, so differences in the outcome come from that factor rather than other influences. For example, when studying how light affects plant growth, you’d keep soil type, amount of water, temperature, and plant type the same across all trials; the light exposure is what changes, and the constants ensure fair comparisons. The other terms describe different concepts: isotonic relates to solutions with equal osmotic pressure, polarity to electrical charges, and adhesion to the sticking of different substances.