Answer:
Date Significance Soviet Union Mission
August 21, 1957 First intercontinental ballistic missile (ICBM) R-7 Semyorka
October 4, 1957 First artificial satellite First signals from space Sputnik 1
November 3, 1957 First dog in orbit (Laika) Sputnik 2
January 31, 1958 First US satellite, detection of Van Allen radiation belts
Explanation:
Answer:
Initially, the ballast tanks are filled with water. The weight of the submarine is equal to the upthrust of the water at the position of the submarine under water. When high pressure air is released into the ballast tanks displacing the water, the weight of the submarine becomes less than the upthrust of the water thus the net force is is upwards and it forces the sub to resurface. This is according to the Archimedes principle which states that a a body partially or wholly immersed in water displaces its own weight of the fluid in which it is immersed.
When you are asked a question like this, you can always ask yourself this question. Can I change it back after this change? For example, if you are burning wood, you cannot bring it back to wood after you burn it, therefore, it is a chemical change. However, if you boil and evaporate water, you can make the water condense again back into its liquid form. In this case, you cannot bring the tomato back to its raw state. Therefore, cooking raw tomatoes is a chemical change.
Answer:
2 moles
Explanation:
The following were obtained from the question:
Molarity = 0.25 M
Volume = 8L
Mole =?
Molarity is simply defined as the mole of solute per unit litre of solution. It is represented mathematically as:
Molarity = mole of solute/Volume of solution.
With the above equation, we can easily find the number of mole of MgCl2 present in 8 L of 0.25 M MgCl2 solution as follow:
Molarity = mole of solute/Volume of solution.
0.25 = mole of MgCl2 /8
Cross multiply to express in linear form
Mole of MgCl2 = 0.25 x 8
Mole of MgCl2 = 2 moles
Therefore, 2 moles of MgCl2 are present in 8 L of 0.25 M MgCl2 solution
