Answer:
( B) They all have their valence electrons in the same type of subshell.
Explanation:
With each period, a new shell is added to the atom.
Further, the groups are classified based on the type of subshell the last electron enters and number of valence electrons.
For all elements of same group, the last electron enters the same type of subshell.
Say, for group 1, last electron enters s orbital and they have 1 valence elctron.
for group 17, last electron enters p orbital and they have 7 valence electrons.
(A) and (D) are wrong because, energy level of the valence electrons is determined by the principle quantum number n and l and not by the type of subshell(only l) they enter.
(C) if the valence electron enters p orbital, then the elements will be placed in the p- block.
The number of same atom needs to be equal at both sides of the equation. According to this rule, we can get the balanced equation: 2C6H14 + 19O2 -> 12CO2 + 14H2O.
Answer:
Explanation:
A physical change is one where only physical, not chemical, properties change. Let's analyze each answer choice.
A. Change in odor
- A change in order is one of the signs of a chemical change.
B. Chopping
- Chopping is a physical change, because no new substances are produced. However, it's not reversible. It's impossible to put something chopped back together again permanently.
C. Phase change
- A phase change is another physical change, plus it is reversible. For example, you can freeze water into ice and melt it back to water.
D. Rusting
- Rusting is a chemical change, because new substances are created.
So, the best answer choice for a reversible physical change is <u>C. phase change</u>.
Remember the saying: King Henry Drinks Dark Chocolate Milk. (KHD|DCM)