Answer:
A molecule of an element is composed of exactly two types of atoms.
Explanation:
B. They came up with the term “radioactivity.”
C. They conducted experiments with uranium-containing minerals and pure uranium.
E. They discovered two new radioactive elements
Answer:
1) 
2) 
3) 

Explanation:
Given:
width of river, 
speed of stream with respect to the ground, 
speed of the swimmer with respect to water, 
<u>Now the resultant of the two velocities perpendicular to each other:</u>



<u>Now the angle of the resultant velocity form the vertical:</u>



- Now the distance swam by the swimmer in this direction be d.
so,



Now the distance swept downward:



2)
On swimming 37° upstream:
<u>The velocity component of stream cancelled by the swimmer:</u>



<u>Now the net effective speed of stream sweeping the swimmer:</u>



<u>The component of swimmer's velocity heading directly towards the opposite bank:</u>



<u>Now the angle of the resultant velocity of the swimmer from the normal to the stream</u>:



- Now let the distance swam in this direction be d'.



<u>Now the distance swept downstream:</u>



3)
Time taken in crossing the rive in case 1:



Time taken in crossing the rive in case 2:



Answer:
Current in each branch will be 2.5 A
Explanation:
We have given that a circuit has three branch each has a resistance of 37.5 ohm
We have also given that a total current of 7.5 A is flows through the circuit
As we know that in parallel circuit total current is the sum of current flowing through each branch
As the resistances of each branch is same so current will also be same
As there is 3 branches in circuit so current in each branch will be 
Answer:d
Viruses do not have organelles
Explanation
Viruses do not have cells; therefore they do not have organelles. Viruses contain genetic material (DNA or RNA) and a way containing and delivering that genetic material into a cell.