Answer: A. silicon and oxygen
Explanation:
The two most abundance elements in earth's crust are silicon and oxygen.
The most abundant element in earth's crust is Oxygen (O) which has a percentage composition of 46.6%. Oxygen is mainly present as silicates, carbonates, sulphates etc.
The second most abundant element in earth's crust is Silicon (Si) which has a percentage composition of 27.7%
. Silicon is present in the form of silicates.
The third most abundant element in earth's crust is aluminium (Al) which has a percentage composition of 8.1 %.
The fourth most abundant element in earth's crust is Iron (Fe) which has a percentage composition of 5.0 %.
In this graph, what is the displacement of the particle in the last two seconds?of the particle in the last two seconds?
<span>0.2 meters
2 meters
4 meters
6 meters</span>
In this graph, the displacement of the particle in the last two seconds is 2 meters.
Answer : The number of molecules of A needed to make 5000 molecules of AB will be, 5000
Explanation :
Law of conservation of mass : It states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form.
The given balanced chemical reaction is,

As per question, molecule B is an excess reagent because it had enough molecule to make 5000 molecules of AB. So, molecule A is limiting reagent.
From the balanced reaction, we conclude that
As, 1 molecule of AB produced from 1 molecule of A
So, 5000 molecule of AB produced from 5000 molecule of A
Hence, the number of molecules of A needed to make 5000 molecules of AB will be, 5000
Answer:
Net force equals 0
Explanation:
Newton's first law states that an object at rest tends to remain at rest, and an object in motion tends to remain in motion with a constant velocity (constant speed and direction of motion), unless it is acted on by a nonzero net force. Note that the net force is the sum of all the forces acting on an object.