Q.1 What are weedicides ? Give some examples.
Q.2 Define the term agricultural practices and also state the
Important steps taken during crop production
Q.3 Why proper depth is important for the plantation of seeds ?
Q.4 Why is it advisable to wash fruits and vegetables before using
them?
Q.5 What is biological control of pest? How is it beneficial?
Q.6 A simple pendulum makes 20 oscillations in 40 seconds. What
is the time period and frequency of its oscillations?
Q.7 When we hear a sound does any part of our body vibrate?
Name the part.
Q.8 Suppose a stick is struck against a frying pan in vaccum. Will
the frying pan vibrate? Will we able to hear the sound? Explain.
Q.9 A vibrating body vibrates 50 times in 5 seconds. Will the sound
be detected by human ear? Why or why not?
Q.10 A period of 5.0 seconds corresponds to a frequency of
Hertz.
Q.11 A tennis coach paces back and forth along the sideline 10
times in 2 minutes. Find out the frequency of her pacing,
CONT
Q.12 Write the word equation and chemical equations for the
following-
a) Reaction of zinc with sulphuric acid
b) Reaction of aluminium with hydrochloric acid.
Q.13 What will happen when
a) When dilute sulphuric acid is poured on a copper plate.
b) When charcoal reacts with oxygen.
c) When Iron reacts with copper sulphate
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Answers
Answer:
Q1. Weeds are unwanted plants growing among wanted crops and compete with crop plants for sunlight, nutrients, water, etc. They will not show any effect on crop plants. Two popularly used weedicides are 2,4-d ethylester ,neem extract, glyphosote etc.
Q2. Agricultural practices mean basically a collection of principles to apply for farm production processes in order to get better agricultural products. They are simply practices used in agriculture to facilitate farming.
Q3.Seeds should be sown at proper depth so that they can get air, water and later on sunlight for development. Also their roots may develop at proper depth to hold plant.
Q4. Washing will help remove bacteria, including E. coli, from the surface of fruit and vegetables. ... It is always advisable to wash all fruit and vegetables before you eat them to ensure they are clean and to help remove bacteria from the outside. Peeling or cooking fruit and vegetables can also remove bacteria.
Q5. Biological control is the beneficial action of parasites, pathogens, and predators in managing pests and their damage. Biocontrol provided by these living organisms, collectively called “natural enemies,” is especially important for reducing the numbers of pest insects and mites.
Answer:
Explanation:
- the fertilizers which are used to remove weeds(unwanted plants)
- The agricultural cycle is the annual cycle of activities related to the growth and harvest of a crop (Plant.) ... The main steps for agricultural practices include preparation of soil, sowing, adding manure and fertilizers, irrigation, harvesting and storage
- Seeds should be sown at proper depth so that they can get air, water and later on sunlight for development. Also their roots may develop at proper depth to hold plant
- to remove dust and some germs on it
- Biological control is the beneficial action of parasites, pathogens, and predators in managing pests and their damage. Biocontrol provided by these living organisms, collectively called “natural enemies,” is especially important for reducing the numbers of pest insects and mites
- Time period = Time taken by the pendulum/Number of oscillations made by the pendulum. Hence, the Time period and frequency are 2 seconds and 0.5 Hertz respectively
- eardrum (tympanic mambrane)
- The frying pan will vibrate. We will not be able to hear the sound of vibration because sound cannot travel in vacuum
- no because the sound frequancy is 10Hz and a human body have hearing range of 20 to 20000 Hz
- no.
- no
- Zn + H2SO4 = ZnSO4 + H2 zinc + salphuric acid -------> zinc sulphate + hidrogen
Al + HCl = AlCl3 + H2