chemistry
Which of these observations is an indication that a chemical reaction has occurred?
A Steam forms above boiling water.
B A solid forms when a clear solution is frozen.
C A solid forms when two clear solutions are mixed.
D Sugar crystals form on the sides of a boiling pot of sugar water
C. A solid forms when 2 clear solutions are mixed
Which of Newton's Laws states that all objects at rest will stay at rest unless acted upon by an unbalanced force?
Newton's 1st Law
Why does the sun appear brighter to people on Earth than any other star
it is the closest star
Farmers can best reduce negative effects on the water quality of nearby streams and lakes by planting crops that
need less fertilizer
What is the powerhouse of the cell?
The mitochondria
One of the properties that makes copper, Cu, useful for household wiring is its ability to conduct electricity. Which other element is most likely to conduct electricity? Gold, Au
Radon, Rn
Bromine, Br
Nitrogen, N
Gold, Au
A student pushes a 51.5 kilogram bookshelf across a smooth floor with a net force of 67 N. What is the approximate acceleration of the bookshelf?
1.3m/s^2
What is the difference between neap and spring tides?
What is a heterotroph?
Something that makes has to eat other organisms/cannot make its own food.
Which two body systems are primarily responsible for locomotion?
skeletal & muscular
Which element has chemical properties that are most similar to the chemical properties of sulfur, S? Silicon, Si
Chlorine, Cl
Selenium, Se
Phosphorus, P
Selenium, Se
A skater pushes off a wall and skates backward for a few meters before stopping. Which statement best describes an action–reaction force pair in this situation?
the skater pushes onto the wall and the wall pushes onto the skater.
what are the 2 conditions needed for hurricanes to form?
warm ocean water and a low pressure system.
Buffelgrass is an invasive species of grass from Africa that outcompetes native Texas grasses for space and water. Which long-term change to a Texas grassland would most likely occur due to the introduction of buffelgrass
the population of native grass will descrease
what are the three parts of the cell theory
1. all living things are made up cells
2. cells are the basic unit of life
3. all cells come from preexisting cells
Oxygen and oxygen-containing compounds are involved in many different reactions. Which balanced equation represents a reaction that involves 14 atoms of oxygen?
NH4Cl + KOH → NH3 + H2O + KCl
2Na + 2H2O → 2NaOH + H2
2C2H6 + 7O2 → 4CO2 + 6H2O
4Fe + 3O2 → 2Fe2O
2C2H6 + 7O2 → 4CO2 + 6H2O
A sledgehammer has a mass of 3.5 kilograms. What net force, to the nearest whole newton, will a person need to apply to accelerate the sledgehammer at a rate of 4.0 m/s2 ?
14N
what is the process in which stars produce their own light?
nuclear fusion
Plants that live on the floors of densely populated forests must compete for sunlight. Which type of leaves are most likely found on plants that are best suited to living on the floor of a dense forest?
F Leaves that are needle-shaped
G Leaves that are smallest
H Leaves that store the greatest amount of water
J Leaves with the greatest amount of surface are
J leaves with the greatest amount of surface area
Students observe an unknown species during a field study. They observe that the organism is multicellular, is autotrophic, and can reproduce both sexually and asexually. Which kingdom does this organism most likely belong to ?
plantae
Two solutions are mixed and react to produce the solid precipitate AgCl. The chemical reaction is shown by the balanced chemical equation. AgNO3 + NaCl → AgCl + NaNO3 What happens to the total mass as the reaction takes place?
the mass remains constant
Two students record the distance they each traveled in 60 seconds in the data table shown. Student 1: Distance (m) = 40 Time (s)= 60. Student 2: Distance (m)= 20 Time (s)= 60. If the students continue at the same speed, which statement describes the total distance traveled after 90 seconds?
Student 1: 60m
Student 2: 30m
Alpha Centauri appears as a bright object visible in the Milky Way galaxy. Alpha Centauri is actually a system of three objects. Each object produces light and rotates on its own axis. The system is an average of 4 light-years from Earth. Based on this information, the three objects that make up the Alpha Centauri system are all-
stars
A farmer digs a small pond in a pasture. The farmer adds young individuals from two species of algae-eating fish to the pond and plants some reeds around the edges of the pond. The farmer wants the pond to be a sustainable ecosystem. How could they?
What function do both cell membranes and cell walls perform?
Allowing water to move into and out of cells