Answer: 95%
Explanation:
To obtain score of 80% on entire exam means the student have to answer
(80/100)×80 = 64 correct answers
Student have already answered 75% of the first 60 questions correctly meaning
(75/100)×60=45 correct answers from first 60 questions
Remaining correct answers s/he have to answer
64-45=19
So from remaining 20 questions s/he have to answer 19 correct questions that is
20 × (x/100) = 19
x = 19 ×(100/20)
x = 95%
Answer:
B. A harmful compound can become harmful when its elements are seperated.
Explanation:
In the question, common table salt, NaCl was the illustration.
NaCl is a crystalline solid whjch has different benefits like for preservation, add taste to foods etc. NaCl is generally consumed by humans daily and is found readily. This goes to show that NaCl is a harmless compound but the individual elements that is, Soduim and Chlorine gas,
2Na + Cl2 --> NaCl
Soduim metal is a reactive and unstable element with 1 (valence) electron in its outer shell. Hence why the reaction of sodium strips with water is explosive.
Chlorine gas is very poisonous, unstable as well as reactive because of the 7 (valence) electrons in its outermost shell.
Answer: True
All the information will be in the book so that mean when you are taking the test you are able to see and find the answers
