Answer:
Yttrium, Silver,Iron,Nickel and Copper I believe
Thermal is the root word of heat
Answer:
A) , ,
A = 1.5×, A = 1.9×, A=1.5×
B) 4.469
Explanation:
From Arrhenius equation
where; K = Rate of constant
A = Pre exponetial factor
= Activation Energy
R = Universal constant
T = Temperature in Kelvin
Given parameters:
taking logarithm on both sides of the equation we have;
since we have the rate of two different temperature the equation can be derived as:
= 19846.04×7.544× = 1.497
= = 4.469
<span>These are five questions and five answers.
</span><span>
</span><span>
</span><span>1. A substance that can be separated into two or more substances only by a chemical change is a.</span><span /><span />
<span>Answer: compound
</span><span />
<span>Explanation:
</span><span />
<span>i) solution is a homogenous mixture and it can be separated by physical media. For example, a brine: you can evaporate the water from the salt by heating the solution (brine)
</span><span />
<span>ii) elements cannot be separated into two or more substances except by nuclear reactions.
</span><span />
<span>iii) mixtures: heterogenous and homogenous mixtures can be separated by physical treatments.
</span><span />
<span>iv) compounds are substaces composed of different elements bonded chemically; only chemical reactions break the chemical bonds or create new chemical bonds leading a compound to form other substances.
2. Which of the following materials is a substance?
</span><span />
<span>Answer: silver
</span><span />
<span>Explanation:
</span><span>
</span><span>Substances have a definite composition that can only be modified by chemical reactions.
</span><span>
</span><span>
</span><span>Elements and compounds are substances.
</span><span>
</span><span>
</span><span>Silver is an element, such as sodium, gold, oxygen. You can find the list of the 118 known elements in a periodic table.
</span><span>
</span><span>
</span><span>Mixtures, either homogenous or heterogeneous, can be separated by physical mechanisms and so they are not substances: air, gasoline, and stainless steel are mixtures because they have not a unique chemical formula but are formed by other compounds or elements in different proportions, i.e. with not a unique chemical formula.</span><span /><span>
3.The first figure in a properly written chemical symbol always is _____.
</span><span />
<span>Answer: capitalized
</span><span />
<span>Explanation:
</span><span>
</span><span>
</span><span>This is a rule to write the symbols of the elements. For example, Na (sodium), Br (bromine), I (iodine), O (oxygen), Ne (neon).</span><span /><span>
4. Which of the following represents a compound?
Answer: H2O
</span><span>
</span><span>Explanation:
</span><span>
</span><span>
</span><span>That is the only chemical formula. The other representations are not valid chemical formulas. A chemical cormula can oly contain chemical symbols and subscript numbers, to represent the kind of atoms (elements) and how many of each (the subscrip).</span><span /><span>
5. What do chemical symbols and formulas represent, respectively?
</span><span />
<span>Answer: elements and compounds
</span><span />
<span>Justification:
</span><span />
<span>1) The symbols are used to represnt elements, such as Na (sodium), Li (lithium), Be (berylium)
2) Chemical formulas represent compunds. For example: CO is carbon monoxide, CO2 is carbon dioxide, H2CO3 is carbonic acid, Na2CO3 is sodium carbonate.
</span><span />
<span>Each compound has a unique chemical formula.
</span>
Answer:
Explanation:
β decay is a process in which a nucleus emits an electron.
The nuclear symbol for a β particle is
l
0
-1
e
.
In any nuclear equation, the sum of the subscripts (atomic numbers,
Z
) and the sum of the superscripts (atomic masses,
M
) must be equal on each side of the equation.
For the β decay of iodine 131, we have
131
53
I
→
l
M
Z
X
+
l
0
-1
e
Hence
131
=
M
+
0
, so
M
=
131
53
=
Z - 1
, so
Z
=
53
+
1
=
54
The element
X
with
Z = 54
is
Xe
.
So the equation is
131
53
I
→
131
54
Xe
+
l
0
-1
e
Note that in β decay, the product has the same mass number but an atomic number that has increased by 1.