If the object's <em>velocity is constant</em> ... (it's speed isn't changing AND it's moving in a straight line) ... then the net force on the object is zero.<em> (D)</em>
Either there are no forces at all acting on the object, OR there are forces on it but they're 'balanced' ... when you add up all of their sizes and directions, they just exactly cancel each other out, and they have the SAME EFFECT on the object as if there were no forces at all.
C. High-visibility clothing is important to wear in areas with moving vehicles
The answer is noble gas. Since noble gas are constant and
unreactive. They can still shape compounds with other elements.
Group 15 is also group 5A and Group 17 is also group 7A. Elements in these sets
do not typically form ionic bonds; they are more on creating covalent bonds
since they're non-metals.
Therefore, that leaves us with B. from Group 1. They are metals (but Hydrogen)
which respond violently with water, and they form ionic bonds, for they drop
outer electrons easily.
HCl + NaOH -> H2O + NaCl
CaCO3 + KI -> K2CO2 + CaI2
AlF3 + Mg(NO3)2 -> Al(NO3)3 + MgF2
The blank distance is your answer
