<span>1 drop is approximately 0.05mL. Since 0.500L of 0.550M NH4Cl contains 0.275mol of substance (calculated by using c=n/V formula), equal amount of substance of NH3 is needed to neutralize this solution (since pH of 7 is neutral solution). Thus, we need 0.0275L of NH3, i.e. around 550 drops.</span>
Answer:
Coal is a traditionally used source of energy, there are main four types of ranks for coal. Here the rank of a coal means to a natural process called Coalification, which takes place during a plant is buried and changes to a harder, and denser material and become even more rich in carbon contents.
Anthracite is know to have the highest ranked coal, it contains highest percent of fixed carbon and lowest percent of volatile material.
Answer:For a typical experiment, you should plan to repeat it at least three times (more is better).
Explanation:
A. False. If it is high tide in one place on Earth, the place exactly opposite to it will also have a <em>high</em> tide.
The gravitational attraction of the Moon and the inertia of the oceans cause <em>two tidal bulges </em>on opposite sides of the Earth.
B. True. Cassini used flybys of Venus, Earth and Jupiter as slingshots to reach Saturn.
C. True. The whole solar system moves around the galaxy.
D. True. If a planet’s gravity is not strong enough, the molecules in its atmosphere will have enough kinetic energy to escape into space.
E. False. The <em>mass of an object is constant</em>, but its <em>weight changes</em> according to the gravity of the planet.
F. False. To find the mass of an object, <em>divide</em> its weight by gravity.
or weight = mass × gravity
∴ <em>Mass = weight/gravity
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