Answer:
About 60.
Explanation:
Mendeleev knew of 63 elements. He wrote their properties on cards and arranged them in order of atomic mass.
That's how he discovered that the properties of elements are periodic functions of their atomic masses.
Answer:
13 km
Explanation:
Distance travelled = 5 km + 3 km + 2 km + 3 km = 13 km
Answer:
3
Explanation:
the answer is 3 because it is 3 for the o2 so 3 you <em>have </em><em>to </em><em>pay </em><em>more </em><em>attention </em><em>for </em><em>the </em><em>small </em><em>ditails </em>