Answer:
An atom consists of a positively charged nucleus, surrounded by one or more negatively charged particles called electrons. The positive charges equal the negative charges, so the atom has no overall charge; it is electrically neutral.
An example is when on a seesaw if a kid is on one side and an adult is on the other then it is unbalanced because the adult weighs more
90% of energy is lost. only 10% is left.
therefore the answer is B. 90%
Answer:
C. fluorine (F) and chlorine (Cl)
D. arsenic (As) and antimony (Sb)
Explanation:
In the periodic table , all the elements are arranged according to the atomic number ,
and the elements are placed in groups and periods ,
The elements with similar chemical and physical properties are placed in a common group .
The elements present in the same group have the same number of valence electrons in the valence shell .
Hence , from the given options ,
fluorine (F) and chlorine (Cl) belongs to group 17 with 7 valence electrons in the outermost shell .
arsenic (As) and antimony (Sb) belong to group 15 with 3 valence electrons in the outermost shell .
