Staar Science

A chemist made the table below to record some atomic properties of four elements. Based on the information in the table, which conclusion about the chemical reactivity of these elements is valid?

• Boron is the most reactive because it has the most protons.

• Fluorine is the most reactive because it has 7 electrons in the outer shell.

• Silicon is the most reactive because it has an equal number of protons and neutrons.

• Gallium is the most reactive because it has many more neutrons than protons.

Tags

NGSS.MS-PS1-1

Which statement about stars is correct?

• Star formation begins in a nebula.

• White dwarfs become main-sequence stars when they gain mass.

• Supergiants are stars that can absorb black holes.

• Main-sequence stars are formed by comets.

Tags

NGSS.HS-ESS1-3

For a laboratory investigation some students put a strip metal into a beaker of blue solution and then stored the beaker on a shelf overnight. The next morning, the students recorded observations about the metal and the solution in the box below. Based on their observations, can the students correctly conclude that a chemical reaction occurred?

• No, because the metal strip was still visible

• Yes, because a new material of a different color formed on part of the metal strip

• No, because the solution stayed blue

• Yes, because the volume of the blue solution stayed the same

Tags

NGSS.MS-PS1-2

Which statement describes the energy changes that occur when water in a tea kettle is heated on a stove that uses natural gas?

• F

• G

• H

• J

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

To fight a bacterial infection, a patient was given an antibiotic to take for 10 days. After the patient finished taking the antibiotics as directed, almost all the bacteria were killed. After another 10 days, the patient was sick again with the same type of infection. What most likely happened?

• A few bacteria survived the antibiotics and stopped reproducing.

• The patient's high fever inactivated the antibiotic, allowing the surviving bacteria to grow rapidly.

• The antibiotic slowed the life cycle of the bacteria.

• Some of the bacteria were resistant to the antibiotic, and they reproduced.

Tags

NGSS.MS-LS4-4

A 1,000 kg car comes uniformly to a stop. If the vehicle is accelerating at -1.2 m/s², which force is closest to the net force acting on the vehicle?

• -9,600 N

• -1,300 N

• -900 N

• -94 BN

Tags

NGSS.MS-PS2-2

The beginning of autumn in North America is in September, but the beginning of autumn in South America is in March. The diagram shows the positions of Earth, the moon, and the sun on one day in September and one day in March. Why does autumn start in different months of the year in North America and South America?

• Earth's orbit around the sun is not a perfect circle.

• North America has a larger landmass than South America.

• The moon has a greater pull on South America than on North America.

• Earth's axis has a 23.5^o tilt.

Tags

NGSS.MS-ESS1-1

This drawing shows a human body system. What is the primary function of this body system.

• The protection of vital organs from injury.

• The chemical breakdown of food into smaller pieces.

• The transport of nutrients, water, and oxygen to body cells.

• The production of hormones that regulate growth and metabolism.

The table lists some compounds found in foods and their formulas. Based on this information, which of these statements is NOT true.

• A molecule of sorbitol contains three oxygen atoms than a molecule of glutamine does.

• A molecule of lactose contains twice as many atoms as a molecule of fructose does.

• A molecule of fructose contains four more atoms than a molecule of glutamine does.

• A molecule of lactose contains twice as many carbons atoms as a molecule of sorbitol does.

Tags

NGSS.MS-PS1-1

An ecosystem that is not sustainable can break down when a natural disaster occurs. This can lead to organisms in the ecosystem either leaving the area or dying off. Increased biodiversity results in a more sustainable ecosystem because -

• a greater number of plant species means that there is less barren land

• a greater variety of species present allows more organisms to adapt after changes occur

• the transition area between two ecosystems is narrow

• there are fewer species to be affected by environmental stresses

Tags

NGSS.MS-LS2-5