Answer:
A.B = -38
Explanation:
A = 2i + 9j and B = -i - 4j.
So, A.B = (2i + 9j).(-i - 4j)
= 2i.(-i) + 2i.(-4j) + 9j.(-i) + 9j.(-4j)
= -2i.i - 8i.j - 9j.i - 36j.j
since i.i = 1, j.j = 1, i.j = 0 and j.i = 0, we have
A.B = -2(1) - 8(0) - 9(0) - 36(1)
A.B = -2 - 0 - 0 - 36
A.B = -38
Answer: 846°C
Explanation:
The quantity of Heat Energy (Q) required to heat bismuth depends on its Mass (M), specific heat capacity (C) and change in temperature (Φ)
Thus, Q = MCΦ
Given that:
Q = 423 joules
Mass of bismuth = 4.06g
C = 0.123 J/(g°C)
Φ = ?
Then, Q = MCΦ
423 J = 4.06g x 0.123 J/(g°C) x Φ
423 J = 0.5J/°C x Φ
Φ = (423J/ 0.5g°C)
Φ = 846°C
Thus, the change in temperature of the sample is 846°C
The answer is c. Continuous direct
Because chemical changes result in different substances, they often cannot be undone. Some chemical changes can be reversed, but only by other chemical changes.
