Is burning sugar a chemical or physical change? Please provide explanation

How much heat is added if 0.814g of water increase in temperature by 0.351 degree c?

How do limiting factors most affect population size? ostop population growthrestrict population growthincrease population sizeresult in positive impactso

How many lone pairs of electrons are on the central atom of no3- and what is the molecular shape? one, trigonal planar zero, trigonal pyramidal zero, trigonal planar one, tetrahedral one, trigonal pyramidal