VARIABLES & EXPERIMENTS
A student wants to find out if the amount of sunlight affects plant growth. What is the independent variable?
Amount of sunlight.
A pencil starts at the 0-cm mark and ends at the 15-cm mark on a ruler. What is its length?
15 centimeters
The chemical symbol Na represents which element?
Sodium
What is the chemical formula for a molecule made of two hydrogen atoms and one oxygen atom?
H₂O
A wooden block floats in water while a metal coin sinks. What property helps explain this difference?
Density
A student changes the temperature of water to see how much sugar dissolves. What is the dependent variable?
The amount of sugar that dissolves.
What metric unit is commonly used to measure the mass of a small apple?
Grams
An atom has 12 protons. What is its atomic number?
12
What is the chemical formula of carbon dioxide?
CO₂
An iceberg floats in the ocean. What does this tell us about the density of ice compared to seawater?
Ice is less dense than seawater.
Here's why:
When water freezes, its molecules spread farther apart and form an open structure.
This makes ice take up more space while having the same mass.
As a result, ice becomes less dense than liquid water.
Since it is less dense than seawater, it floats on the surface.
A student tests whether adding fertilizer helps plants grow taller. Which variable is being changed?
The amount of fertilizer.
Which of the following is a quantitative observation: smooth texture, red color, sweet smell, or 25 grams?
25 grams
Which two subatomic particles are found inside the nucleus of an atom?
Protons and neutrons.
Water droplets stick to the outside of a glass. What property of water does this demonstrate?
Adhesion
An ice cube is placed outside on a warm day. What happens when it absorbs thermal energy?
It melts and changes from a solid into a liquid.
A hypothesis states: "If I increase the amount of water given to a plant, then the plant will grow taller." What is the dependent variable?
The height or growth of the plant.
A small caterpillar measures 3.8 centimeters on a ruler. How many millimeters long is it?
38 millimeters.
An atom has 9 protons and 10 neutrons. What is its mass number?
19
A water strider can walk on the surface of a pond. What property of water allows this to happen?
Surface tension
A frozen puddle begins melting when the temperature rises above 0°C. Where does the thermal energy come from?
The warmer surrounding air transfers thermal energy to the ice.
A student investigates whether changing the type of soil affects how quickly a seedling grows. Identify the independent and dependent variables.
Independent: Type of soil.
Dependent: Growth rate of the seedling.
A student measures the mass of a rock using a triple-beam balance. Which physical property is being measured?
Mass
An element has an atomic number of 13 and an atomic mass of approximately 27. How many neutrons does it have?
14 neutrons.
Why is water called the universal solvent?
Because it can dissolve many different substances.
A student observes that water droplets form on the leaves of a plant early in the morning. What process allows plants to release excess water vapor into the atmosphere through their leaves?
Transpiration