Sr is below Ca and to the right of Rb in the Periodic Table (see the attached image).
Reactivity increases from <em>top to bottom of a Group</em>. Sr is below Ca, so it is <em>more reactive</em> than Ca.
Reactivity decreases from <em>left to right in a Period</em>. Sr is to the right of Rb, so it is <em>less reactive</em> than Rb.
Answer: Option (a) is the correct answer.
Explanation:
When two or more atoms are chemically combined together then the product formed is known as a molecule.
These atoms can be bonded through either covalent or ionic bonds.
For example, a water molecule consists of two hydrogen atoms combined with an oxygen atom. Chemical formula of water is 
.
Thus, we can conclude that an element can be made of many elements.
Answer:
B. 126
Explanation:
the scale is 1 to 42 so the scale would be:
3 cm:x cm
3 * 42 = 126 cm
Answer:
7.81 moles
Explanation:
To solve this problem, let us generate an expression involving volume and number of mole of the gas since the pressure and temperature of the gas are constant.
From ideal gas equation:
PV = nRT
Divide both side by P
V= nRT/P
Divide both side by n
V/n = RT/P
Since RT/P are constant, then:
V1/n1 = V2/n2
Data obtained from the question include:
V1 = 4.11
n1 = 2.51 moles
V2 = 16.9L
n2 =?
Using the above equation i.e V1/n1 = V2/n2, the final number of the gas can be obtained as illustrated below:
4.11/2.51 = 16.9/n2
Cross multiply to express in linear form
4.11 x n2 = 2.51 x 16.9
Divide both side by 4.11
n2 = (2.51 x 16.9) / 4.11
n2 = 10.32moles
Now, to obtain the number of mole of the gas added, we'll subtract the initial mole from the final mole i.e
n2 — n1
Number of mole added = n2 — n1
10.32 — 2.51 = 7.81 moles
Therefore, 7.81 moles of the gas was added to the container
Explanation:
An observation that can be counted is known as quantitative observation. On the other hand, an observation that does not contain any numerical data is known as non-quantitative observation.
Therefore, given observations are classified as follows.
(a) The Sun rises in the east - It is a non-quantitative observation as it cannot be measured.
(b) A person weighs one-sixth as much on the Moon as on Earth - It is a quantitative observation as it can be measured because we know the mass of moon. Hence, we can find out the weight of person.
(c) Ice floats on water - It is a non-quantitative observation as it cannot be measured.
(d) A hand pump cannot draw water from a well more than 34 ft deep _ It is a quantitative observation because it is measure that more than 34 ft deep water cannot be drawn by the pump.
