Study Guide 1st Semester Exam

James is conducting an experiment to see how different amounts of sunlight affect plant growth. He keeps one plant in normal sunlight conditions to see how much a regular plant would be expected to grow. This plant serves as a _____ in his experiment.

• dependent variable

• independent variable

• constant

• control

Answer explanation

A control is a standard of comparison in experiments. It helps determine the effects of the independent variable by providing a baseline, such as a plant grown under normal conditions to compare against the experimental group.

Mia is preparing a large batch of cookies and needs 4.6 kg of flour. How many grams of flour does she need?

• 460

• 4,600

• 46,000

• 46,000,000

Answer explanation

To convert kilograms to grams, multiply by 1000. Thus, 2.4 kg x 1000 = 2400 grams. The correct answer is 2400.

Hannah is filling up water bottles for a school event. She has a large container with 65.8 L of water. How many milliliters of water does she have?

• 65,800

• 6,580

• 0.658

• 0.0658

• 0.0000658

Answer explanation

To convert liters to milliliters, multiply by 1,000. Thus, 42.3 L x 1,000 = 42,300 mL. Therefore, the correct answer is 42,300.

During a science class, Zoe asked her teacher what the nucleus of an atom contains.

• Protons and neutrons.

• Protons and electrons.

• Neutrons and electrons

• Electrons and protons

Answer explanation

The nucleus of an atom contains protons and neutrons, which are the two types of nucleons. Protons carry a positive charge, while neutrons are neutral. Electrons, on the other hand, are found in the electron cloud surrounding the nucleus.

During a science fair, Isla was asked to identify the negatively charged subatomic particles in atoms. What should she answer?

• Protons.

• Electrons.

• Neutrons.

• Ions.

Answer explanation

Electrons are the negatively charged subatomic particles in atoms. Protons are positively charged, neutrons are neutral, and ions are charged atoms or molecules, not subatomic particles.

In a science class, Harper is learning about atoms. Her teacher asks her, "Harper, can you tell me what the atomic number of an atom represents?"

• The number of protons in the atom.

• The number of electrons in the atom.

• The number of neutrons in the atom.

• The number of protons, electrons, and neutrons in the atom.

• The net electrical charge of the atom.

Answer explanation

The atomic number of an atom is defined as the number of protons it contains. This determines the element's identity and its position in the periodic table, making "The number of protons in the atom" the correct choice.

James is curious about the components of an atom while studying chemistry. He wants to understand what the atomic mass of an atom is.

• The number of protons in the atom.

• The number of electrons in the atom.

• The number of neutrons in the atom.

• The number of protons and neutrons in the atom.

• The number of protons, electrons, and neutrons in the atom.

Answer explanation

The atomic mass of an atom is determined by the total number of protons and neutrons, as these particles contribute most to the mass. Electrons have negligible mass, making the correct choice the number of protons and neutrons.

When David and Isla were discussing chemistry, David explained that a(n) __________ forms when two atoms transfer electrons.

Answer explanation

A(n) ionic bond forms when two atoms transfer electrons. This type of bond occurs between a metal and a non-metal, where the metal loses electrons and the non-metal gains them, resulting in charged ions that attract each other.

Kai is learning about the periodic table in his chemistry class and encounters Chlorine, which has an atomic number of 17 and an atomic mass of 35. How many electrons does a neutral atom of Chlorine have?

• 20

• 27

• 7

• 17

• 28

Answer explanation

A neutral atom has an equal number of protons and electrons. Fluorine has an atomic number of 9, which means it has 9 protons and therefore 9 electrons. Thus, the correct answer is 9.

While playing with water, Aiden noticed that water droplets tend to merge together on a surface. This tendency of water molecules to stick to each other is referred to as:

• Adhesion.

• Polarity.

• Cohesion.

• Transpiration.

• Evaporation

Answer explanation

The tendency of water molecules to stick to each other is called cohesion. This property arises from hydrogen bonding, allowing water to form droplets and maintain surface tension.