Which of these reactions can be classified as double replacement reactions?

zn + 2hcl → zncl2 + h2

2nacl + f2 → 2naf + cl2

2albr3 + 3k2so4 → 6kbr + al2(so4)3

2k + mgbr2 → 2kbr + mg

Which statement correctly identifies the scientific question and describes why the question is scientific? question 1 refers to the supernatural.question 2 reflects a moral or social value.question 3 refers to something that can be measured.question 4 reflects a question that can’t be observed.

What is happening when the water inside a kettle heats up and begins to boil

Plzz a sample of table sugar (sucrose, c12h22o11) has a mass of 7.801 g. ● a) calculate the number of moles of c12h22o11 in the sample b) calculate the number of moles of each element in c12h22o11 (number of moles of c, number of moles of h & number of moles of o) in the sample. (use your answer from part a as your starting point.) show your work and highlight your final answer. calculate the number of atoms of each element in c12h22o11 (number of atoms of c, number of atoms of h & number of atoms of o) in the sample. (use your answers from part b as your starting for each element.) show your work and highlight your final answer.