A substance was analysed and was found to have a boiling point of 450 °C. At room temperature it is a soft grey solid. Which temperature could be the melting point of a pure sample of the substance?A-12 °CB56 °C to 72°CС250 °C to 275 °CD142 °C

When water dissociates, each water molecule splits into a hydroxide ion and a) h 3 o + b) a hydrogen atom c) a hydrogen ion d) h 2 o e) oh —

Which statement about hf is true? it is zero for any compound in its standard state. it is positive when the bonds of the product store more energy than those of the reactants. it is negative when a compound forms from elements in their standard states. it is zero for any element that is in the liquid state.

Determine the ph of 0.10 m nh3 solution. nh3 is a weak base with a kb equal to 1.8 x 10-5 round answer to nearest whole number.