Pangea was formed in the Paleozoic Era
In order to get the sum of 2.7 and 2.47, we will add both numbers. So, 2.7 plus 2.47 would be 5.17. And the correct number of significant digits in this number is still the same, 5.17, so we have three significant numbers. Why? There are three rules in identifying the significant figures: 1. Non zeros are always significant (which this applies in our sum above). 2. Any zeros in between significant numbers are always significant. 3. <span> The final zero or zeros in the decimal portion only are significant.</span>
Number of neutrons.
The atomic number is a way of identifying elements so if the were all the same than that wouldn't work very well :)
Answer: The correct option is D.
Explanation: Nonmetallic minerals are the chemical elements from which no new product can be formed when they are melted. For Example: Sand, marble etc..
For the given options:
Option A: Wood is a type of cellulose and is not considered as a nonmetallic mineral resource.
Option B: Iron is an element because it is the smallest substance which cannot be broken down. It is not considered as a nonmetallic mineral resource.
Option C: Coal is a mixture of carbon compounds. This is very close to mineral but is an organic mineral because it contains carbon atom. Hence, it is not considered as a nonmetallic mineral resource.
Option D: Aggregate is formed by the collection of particles forming a whole mass. This is a non-metallic resource as it cannot form any new product.
Hence, the correct option is D.
Answer:
Reasonable Second step- 
Explanation:
The given single step chemical reaction is as follows.
Suppose a two-step mechanism is proposed for this reaction,
The reaction occured in two steps they are as follows.
