Please, I need help with this badly: Substance A has a normal melting point of -25.0 °C, an enthalpy of fusion of 1200 J g'; specific
heat for the solid is 3.00 Jg'c and the liquid is 6.20 J g''C'' Determine the heat needed to
change 150 grams of A from a solid at - 40.0 °C to a liquid at +70.0°c. Draw the diagram to
illustrate the process that is occurring.

How does a catalyst increase the speed of a reaction? a. the catalyst eliminates the activated complex stage, allowing products to form immediately. b. the catalyst lowers the energy level of the reactants, making it easier for them to react. c. the catalyst makes it easier for the activated complex to form, lowering the activation energy. d. the catalyst raises the energy level of the products, making the reaction finish sooner. reset next

What is a number added in front of a formula in order to balance the equation

What element has similar physical and chemical properties as boron.