A toy car rolls down a straight inclined track and its speed increases steadily. At the moment when the car reaches the flat surface at the base of the track, its speed remains constant. Which statement best explains why the speed of the car remains the same when it reaches the flat surface? The forces on the car are balanced.

Gravity is no longer acting on the car.

The force of the track acting on the car slows it down.

Frictional force is greater on the flat surface of the track.

Astudent is given a sample of a blue copper sulfate hydrate. he weighs the sample in a dry covered porcelain crucible and got a mass of 23.875 g for the crucible, lid, and sample. the mass of the empty crucible and lid was found earlier to be 22.652 g. he then heats the crucible to expel the water of hydration, keeping the crucible at red heat for 10 minutes with the lid slightly ajar. on colling, he finds the mass of crucible, lid, and contents to be 23.403 g. the sample was changed in the process to very light clue anhydrous cuso4. if there are again 100.0 g of hydrate, how many grams of cuso4 are in it? how many moles of cuso4? (hint: molar mass of cuso4 = 159.6 g / mole. what per cent of the hydrate is cuso4? you may convert the mass of cuso4 to moles.)

Joan writes four numbers on the board in standard form, and then she writes their scientific notation

Acrystal that absorvd water from air is (blank)a. aqueousb. homogenousc. hygroscopicd. efflorescent