____ is a typical photolithoautotroph. A: Sulfur oxidizing bacteria B: Iron oxidizing bacteria C: Cyanobacteria D: Purple non-sulfur bacteria

sulfur dioxide() A: 二氧化硫 B: 二氧化碳

The main social services of the iron and steel industry system are the provision of iron and steel products and the consumption of iron ore A: 正确 B: 错误

1803a8273f88c11.png 的英文名称是______。 A: iron (II) carbonate B: ferrous carbonate C: iron carbonate D: ferric carbonate E: iron (III) carbonate

e. Vitamin C supplements may be combined with iron supplements to increase iron absorption.

According to the passage, how did Bessemer method make the mass production of steel possible A: It directed air at melted iron in a furnace, removing all impurities. B: It slowly heated iron ore then stirred it and heated it again. C: It changed iron ore into iron which was a substitute for steel. D: It could quickly find deposits of iron ore under the ground.

The mass of a single iron atom is 9.3 × 10–23 g. Determine the number if iron atoms in regular cube that measures exactly 10 cm on an edge. The density of iron is 7.86 g/cm3  (   )

The most significant constituents of coal are . A: hydrocarbons B: sulfur C: oxygen D: nitrogen

In ancient time，there was no iron casting，so the needles were made of ______. A: stone B: tree C: iron D: mental

中国大学MOOC: when a bar of iron attracts other pieces of iron，it ____a magnet，and thus the attraction is called mangnetism.