Jean used an electronic scale to measure the mass of a rock: 40g. Then through the displacement method, she measured its volume: 10 mL. What is the density of the rock? 400 g/mL

4 g/mL

0.25 g/mL

40 g/mL

An open cart is moving along a straight frictionless horizontal track. when rain starts falling vertically into the cart, what happens to the speed of the cart?

How do we measure or think of speed in the united states?

The first-order reaction a→2b+c has rate constant 0.538 s−1. if the initial concentration of a is 0.867 mol l−1, what is the half-life of the reaction in seconds? remember to use correct significant figures in your answer (round your answer to the nearest hundredth). do not include units in your response.