Matter around us is found in the form of elements, compounds and Mixtures. The elements contain atoms of only one type. Around the
Year 1800, only 30 elements showing different properties were known.
Scientists of that age discovered a pattern in their properties and based
On that pattern, several attempts were made to classify elements. The
Earliest attempt was to classify the elements as metals and non-metals.
The latest is the ‘Modern Periodic Table’. This table consists of 7 periods
And 18 groups. Each element of a group in the periodic table has the
Identical outer shell electronic configuration. In other words, the groups
In the periodic table signify an identical outer shell electronic
Configuration. As we go down the group in the periodic table, the number
Of shells increases.
3(a) Write the need to classify elements. 1
3(b) how many groups are there in the ‘Modern Periodic Table’? 1
3(c) which one of the following statements is not correct about the ‘Modern Periodic Table’? 1
(A) It is based on atomic masses.
(B) The position of isotopes is not disputed.
(C) The position of isotopes is easily assigned.
(D) It separates metals from non-metals.
3(d) the cause of periodicity of properties of elements is 1
(A) Increasing atomic radius
(B) Increasing atomic mass
(C) Increasing nuclear charge
(D) The recurrence of similar outer electronic configuration

The organism shown is a free-living one that is anchored to the bottom of ponds and streams during one stage of its life cycle what is the common name for the group to which this organism belong

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1. an experiment in your science class lists the materials needed for the lab. it is your job, as a lab partner, to measure out 25 ml of distilled water and 2.5 grams of magnesium. what lab measuring tools would you choose to measure each substance and how would you use each tool to get the correct amounts? be sure to describe the process you would follow step-by-step. (5 points) 2.which of the following is an si base unit for measuring mass? (2 points) ampere gram meter pound 3.which of the following is an si base unit for time? (2 points) decades hours minutes seconds 4.which of the following tools should a scientist use to measure an object in milligrams? (2 points) graduated cylinder pan balance tape measure thermometer 4.which of the following tools should a scientist use to measure an object in milligrams? (2 points) graduated cylinder pan balance tape measure thermometer. 5.a pencil beside a metric ruler. the ruler is scaled from 1 centimeter to 10 centimeters, with markings for millimeters between each number. one end of the pencil is beside the 0 on the ruler, and the pencil point is beside the 5. which of the following measurements is accurate but not precise? (2 points) 5 mm 5 cm 50 mm 50 cm 6. which of the following prefixes represents the largest value? (2 points) giga hector kilo milli 7. which of the following types of graphs is best for plotting the percentages of a whole value in a data set? (2 points) bar graph circle graph histogram line graph