Which group is least reactive of all the elements

Which of these would be caused by a chemical change? a) the formation of lava. b) sedimantary rock layering over time. c) metamorphic rock forming from igneous. d) metamorphic rock eroding to form sedimentary rock.

Balance and in which category does it fit in? single or double displacement or synthesis or decomposition? (a) k2 o → k + o2 (b) na + i2 → nai (c) cu(no3 )2 + naoh → cu(oh)2 + nano3 (d) kclo3 → kcl + o2 (e) ca(no3 )2 + hbr → cabr2 + hno3 (f) sn(oh)2 → sno + h2 o (g) p4 + n2 o → p4 o6 + n2 (h) fe + al2 (so4 )3 → feso4 + al (i) alcl3 + na2 co3 → al2 (co3 )3 + nacl (j) c3 h6 + o2 → co2 + h2 o

He table below gives the atomic mass and relative abundance values for the three isotopes of element m. relative abundance (%) atomic mass (amu) 78.99 23.9850 10.00 24.9858 11.01 25.9826 what is the average atomic mass (in amu) of element m? 2.86 5.36 24.30 24.98