Answer: Halogens
Explanation:
Halogens include elements like Fluorine, Chlorine, Iodine and Bromine. These elements can be dangerous to humans especially when used in large quantities.
When combined with other elements however, they can form very useful materials. Chlorine for instance forms salt when combined with sodium. Fluorine becomes very useful in toothpaste to protect teeth and bromine can be used in pesticides.
Answer:
V2= 531.4 ml
Explanation:
T1= 273+45 °C= 318 Kelvin
T2= 273+65 °C= 338 Kelvin
V1= 500ml *( 0.001L/1ml)= 0.5 Liters
V2= 
= 
= 0.5314465409 Liters* (1 ml/0.001 L)= 531.4 ml
A physical change is a change to a sample of matter in which some properties of the material change, but the identity of the matter does not. Physical changes can further be classified as reversible or irreversible. The melted ice cube may be refrozen, so melting is a reversible physical change.
Answer: pure substances.
Explanation:
The given substances are:
All what surrounds us, which has mass and occupies spaces, is matter. There are two kind of matter: pure substances and mixtures.
Pure substances have a uniform and constant composition. On the other hand, mixtures are combinations of two or more pure substances in any arbitratry ratio.
Pure substances may be elements or compounds. The elements are the substances conmposed by one only kind of atom. In the list of substances given, Li and O₂ are elements: all the atoms in Li are lithium, and all the atoms in O₂ are oxygen atoms.
Compounds are the chemical combination of two or more different kind of atoms. In the given list H₂O₂ and NaCl are compounds. As you see, H₂O₂ contains atoms of hydrogen and oxygen, chemically bonded, in a fixed ratio (2 atoms of hydrogen by 2 atoms of oxygen). And NaCl has atoms of Na (sodium) and Cl (chlorine), chemicaly bonded, in a fixed ratio (1:1).
There are only 118 known elements and you can find them in any modern periodic table. Therer are virtually infinitely many compounds since many different combinations of the elements can be attained.
Elements and compounds have in common that they are classified as pure substances.
In order to do conversion on these types of problems. <span>
1.You first have to determine the relationship and the current unit and the target unit which it will be converted into.</span> <span>
2.In this case feet to meters and seconds to minutes</span> <span>
3.Determine the conversion rate: </span>1mi =1609 m<span /> and 1 h = 3600 sec; <span>
4.You first calculate: 1230 m x </span>1 mi/1609 m = 0.764 mi/s
<span>5.<span>Next, is the time which is 0.764 mi/s x 3600s/1hr = </span></span><span>2752.02 mi/h
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