Which statement is true? speed is a scalar quantity and velocity is a vector quantity. speed and velocity are both scalar quantities. speed and velocity are both vector quantities. speed is a vector quantity and velocity is a scalar quantity. speed and velocity are neither a scalar quantity nor a vector quantity.

Answer : The correct option is, Speed is a scalar quantity and velocity is a vector quantity.

Explanation :

Speed : It is defined as the distance traveled by the object per unit time. It is a scalar quantity because it does not depends on the direction of an object but it depends on the magnitude of the object. The unit of speed is, meter/second or m/s.

For example : The speed is written as, 44 m/s.

Velocity : It is defined a the displacement of an object with respect to the time. It is a vector quantity because it depends on both direction and as well as on magnitude of the object. The unit of velocity is, meter/second or m/s.

For example : The velocity is written as, 44 m/s north.

Hence, the correct option is, Speed is a scalar quantity and velocity is a vector quantity.

answer is: nuclear fusion produces elements that are heavier than helium.

nuclei combine to form a heavier nucleus, releasing energy.  

for example, fusion of hydrogen atoms at the sun.  

this fusion nuclear reaction is in the inner core of the sun and hydrogen (atomic number 1) is conveted into helium (atomic number 2).  

the inner core is the central region of the sun and all solar energy is produced in the core by nuclear fusion.