Answer:
A & D
Explanation:
A single-displacement reaction is a chemical reaction whereby one element is substituted for another one in a compound and thereby generating a new element and also a new compound as products.
From the options, only options A & D fits this definition of single-displacement reactions.
For option D: Both left and hand and right hand sides each have one element and one compound. We can see that K is substituted from KBr to join Cl to form KCl and Br2 on the right hand side.
For option A: Both left and hand and right hand sides each have one element and one compound. We can see that OH is substituted from 2H2O to join Mg to form Mg(OH)2 and H2 on the right hand side.
The other options are not correct because they don't involve only and element and a compound on each side of the reaction.
Answer:
6.14 s
Explanation:
The time the rocket takes to reach the top is only determined from its vertical motion.
The initial vertical velocity of the rocket is:
where
u = 100 m/s is the initial speed
is the angle of launch
Now we can apply the suvat equation for an object in free-fall:
where
is the vertical velocity at time t
is the acceleration of gravity
The rocket reaches the top when
So by substituting into the equation, we find the time t at which this happens:
