Sharping a pencil leaves behind pencil shavings. Is sharpening pencil a physical or chemical change

Each element has its own emission bright line spectrum pattern. True or false?

How does the vapor pressure of water at 10 c compare with its vapor pressure at 50 c?

Can water lakes and rivers evaporate

a pure aluminium block with a mass of 10g is heated so that its temperature from 20C to 50C. The specific heat capacity of aluminium is 8.99 x 10^-1 J/gK. which expression gives the heat energy change in kJ

Consider a bathtub filled with water, with a plug in the drain. How long would this be considered a closed system?

What is the relative charge carried by an electron

Which term best describes the type of bonding in magnesium chloride

This equation indicates that the reaction gives off heat. What is this type of reaction called? 2C4H10 + ? O2? 8CO2 + 10H2O + heat a. an exothermic reaction b. an endothermic reaction c. absorption reaction d. precipitation reaction

Given the balanced equation representing a reaction: C3H8 (g) + 5O2 (g) = = >3CO2 (g) + 4H2O (g) What is the total number of moles of O2 (g) required for the complete combustion of 1.5 moles of C3H8 (g) ? (1) 0.30 mol (3) 4.5 mol (2) 1.5 mol (4) 7.

What increases in equal steps of one from left to right in the Periodic Table for the elements lithium to neon?