Mr(NH4)2SO4 = (14+4) * 2 + 32 +16 * 4 = 36+32+64 = 132
Mr(NH4HCO3) = 14+4+1+12+16 * 3 = 31+48 = 79
Mr(NH4H2PO4) = 14+1 * 4 + 1 * 2 + 31+16 * 4 = 14+4+2+31+64 = 115
Mr(KH2PO4) = 39+1*2+31+64=41+95=136
Mr(H2TeO4) = 2+128+64=194
Mr(Cr(SO4)3) = 52+(32+64)*3=52+96*3=52+288=340