Answer:
B. 4 ml
Explanation:
Volume displacement of the hammer = volume volume of water when the hammer was placed into the cylinder - volume of water only before the hammer was placed into the cylinder.
Volume volume of water when the hammer was placed into the cylinder = 69 ml
Volume of water only before the hammer was placed into the cylinder = 65 ml
Volume displacement of the hammer = 69 ml - 65 ml = 4 ml
<span>While
treating food with gamma rays kills microorganism by damaging their DNA, the energy
of gamma rays rips off electrons from atoms hence ionizing them (causing free radicals).
However, gamma rays do not make the food atoms radioactive. The body has a natural
mechanism of riding the body of free radicals. However, large quantities of radicals in the body can cause
damage.</span>
The elements in Groups 1A(1) and 7A(17) are all quite reactive.
<h3>Major difference between Groups 1A(1) and 7A(17) : </h3>
Group 7's halogens, which are non-metal elements, become less reactive as you move down the group. In contrast to the alkali metals in Group 1 of the periodic table, this trend is the opposite. The most reactive element in Group 7 is fluorine.
Alkali metals are soft and reactive metals. They react vigorously with water and become more reactive. And other hand halogens are reactive non metals.
- Elements of group 1A are known as alkali metals. Elements of this group are lithium, sodium, potassium, rubidium, cesium.
- Reactivity increase down group 1 but decrease up group 7 this is because group 7 elements react by gaining an electron. As one move down the group, the amount of electron shielding increases, meaning that the electron is less attracted to the nucleus.
To know more about Groups 1A(1) and 7A(17) please click here :
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Answer:
The correct answer is b polar covalent
Explanation:
When two atoms joined by covalent bond has difference in their electronegativities at that time polarity arise.
When the electronegativity difference is low such as 1.3 then the polar bond formed by the two atoms are called polar covalent bond.For example H2O
on the other hand polar bond formed by two atoms having high difference in their electronegativities is called ionic bond.For example NaCl.
