bad.py

good_value=True
for comp in [('SiO2', (30, 40)),
             ('NaCl', (20, 30)),
             ('O2', (50, 60)),
             ('C', (100, 120)),
             ('K', (13, 14))]:
  if comp[1][0]>data[comp[0]] or comp[1][1]<data[comp[0]]:
    good_value=False

if good_value:
  print(data)

good.py

comps = [
  ('SiO2', (30, 40)),
  ('NaCl', (20, 30)),
  ('O2', (50, 60)),
  ('C', (100, 120)),
  ('K', (13, 14)),
]

for element, (low, high) in comps:
  if not (low <= data[element] <= high):
    break
else:
  print(data)