calculate the volume of hydrogen produced at s. t.p when 25g of zinc are added to excess dilute hydro chloric acid at 31 degree c and 778 mmHg pressure. H=1, Zn=65, Cl=35.5. Molar volume of gas at s. t.p=22.4dm3 Wikipedia show all workings

Which of the following is an example of physical change not a chemical change? a) a log gives off heat and light as it burns. b) a tree stores energy from the sun in its fruit. c) a penny lost in the grass slowly changes color. d) a water pipe freezes and cracks on a cold night.

Use the half-reactions of the reaction au(oh)3 + hi -> au +i2 +h2o to answer the questions

Which substance produces hydroxide ions in solution? a. an arrhenius acid b. an arrhenius base c. a brønsted-lowry acid d. a brønsted-lowry base e. an amphoteric substance