Answer:
The second option
Explanation:
Speed is defined at the rate at which distance changes with time. It is scalar quantity and it is expressed as shown below:
Speed = 
At constant speed the rate of change of distance with time is the same. On the second graph, this is noticeable. Both distance and time change at the same rate.
it means two oxygen atoms
Answer:
They are:
Length - meter (m)
Time - second (s)
Amount of substance - mole (mole)
Electric current - ampere (A)
Temperature - kelvin (K)
Luminous intensity - candela (cd)
Mass - kilogram (kg)
Answer:
transition elements
Explanation:
Metalloids are elements that have properties intermediate between those of metals and nonmetals. They are sometimes referred to as semi-metals. These materials have recently found great application in materials science and information technology.
Transition elements are however renowned for high densities and tensile strength. The transition elements have the highest density of all the element groups in the periodic table and also have resistance to corrosion. Transition metals such as gold silver and lead are coinage metals because they are resistant to corrosion.
Alkali and alkaline earth metals tarnish easily due to their high reactivity. They are usually very soft metals.
When iron loses the 2 4s electrons, it attains a valency of +2. Sometimes, iron will also lose one of the paired electrons from 3d orbital, leaving the entire 3d orbital filled with unpaired electrons (which provides a more stable configuration). In this case, its valency will be +3.
