How can a device warm food without using fire or electricity

Ineed this asap part i: scientific method what is the difference between science and pseudoscience? what is the scientific method?

Uranium can supply energy for the worlds electricity without admitting harmful greenhouse gases which of these statements best describes an outcome of uranium mining

When the chemicals iron sulfide (fes) and hydrochloric acid (hcl) are combined, bubbles appear from the mixture. 1. does the appearance of bubbles indicate a physical or chemical change? 2. why do the bubbles indicate this change? 3. what property is this?