Is the thin cover that stops food and liquid from entering the larynx

Your town is considering building a biodiesel power plant describe at least two advantages and two disadvantages

Assume you measured the mass of the cart to be (500 ± 1) g and the mass of the additional mass you put on the cart to be (500 ± 1) g as well. since the scale you are using in the lab cannot measure objects heavier than 600g you will have to sum up individual pieces and propagate the error. so what would be the mass and the standard error of the cart and the mass

Which bonds are found inside a water molecule