Unable to load sdf file.

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Hello all, I want to load an SDF file but it keep showing an error:

[ERROR] [1678635055.839001, 0.000000]: Invalid XML: mismatched tag: line 90, column 2

Following is the detailed output:

[ INFO] [1678635055.628607023]: waitForService: Service [/gazebo/set_physics_properties] has not been advertised, waiting...
[ INFO] [1678635055.631133677]: waitForService: Service [/gazebo_gui/set_physics_properties] has not been advertised, waiting...
[ERROR] [1678635055.839001, 0.000000]: Invalid XML: mismatched tag: line 90, column 2
[spawn_sdf-5] process has died [pid 7596, exit code 1, cmd /opt/ros/melodic/lib/gazebo_ros/spawn_model -file /home/ibrrahim/catkin_workspaces/learning_ros_ws/src/exmpl_models/small_checkerboard/small_checkerboard.sdf -sdf -model small_checkerboard -x -0.03 -y -0.03 -z 0.2 __name:=spawn_sdf __log:=/home/ibrrahim/.ros/log/e0047cf4-c0ea-11ed-967e-441ca87fed69/spawn_sdf-5.log].
log file: /home/ibrrahim/.ros/log/e0047cf4-c0ea-11ed-967e-441ca87fed69/spawn_sdf-5*.log

Here is my sdf file, it does not seem any problem to me at line-40.

<?xml version='1.0'?>
<sdf version="1.4">
<model name="small_checkerboard">
    <pose>0 0 0 0 0 0</pose>
    <static>false</static>
      <link name="small_checkerboard">
        <pose>0.0 0.0 0.0 0.0 0.0 0.0</pose>
        <inertial>
          <mass>0.01</mass>
          <inertia>
            <ixx>0.083</ixx>
            <ixy>0.0</ixy>
            <ixz>0.0</ixz>
            <iyy>0.083</iyy>
            <iyz>0.0</iyz>
            <izz>0.083</izz>
          </inertia>
        </inertial>
        <collision name="collision">
          <geometry>
            <box>
              <size>0.01 0.01 0.002</size>
            </box>
          </geometry>
        </collision>
      <visual name="sqr11">
        <geometry>
          <box>
            <size>0.01 0.01 0.002</size>
          </box>
        </geometry>
    <material>
          <ambient>0 0 0 1</ambient>
          <diffuse>0 0 0 1</diffuse>
          <specular>0.1 0.1 0.1 1</specular>
          <emissive>0 0 0 0</emissive>
        </material>
      </visual>
  </model>
</sdf>

Line-39 is: </model> which is second last line. Any help would be highly appreciated. Here is my launch file:

<launch>
  <!-- ######################################################################################################## -->

  <arg name="paused" default="false"/>
  <arg name="use_sim_time" default="true"/>
  <arg name="extra_gazebo_args" default=""/>
  <arg name="gui" default="true"/>
  <arg name="headless" default="false"/>
  <arg name="debug" default="false"/>
  <arg name="physics" default="ode"/>
  <arg name="verbose" default="false"/>
  <arg name="world_name" value="$(find simple_camera_model)/simple_camera.world"/>

  <group if="$(arg use_sim_time)">
    <param name="/use_sim_time" value="true" />
  </group>

  <arg unless="$(arg paused)" name="command_arg1" value=""/>
  <arg     if="$(arg paused)" name="command_arg1" value="-u"/>
  <arg unless="$(arg headless)" name="command_arg2" value=""/>
  <arg     if="$(arg headless)" name="command_arg2" value="-r"/>
  <arg unless="$(arg verbose)" name="command_arg3" value=""/>
  <arg     if="$(arg verbose)" name="command_arg3" value="--verbose"/>
  <arg unless="$(arg debug)" name="script_type" value="gzserver"/>
  <arg     if="$(arg debug)" name="script_type" value="debug"/>

  <node name="gazebo" pkg="gazebo_ros" type="$(arg script_type)" respawn="false" output="screen"
    args="$(arg command_arg1) $(arg command_arg2) $(arg command_arg3) -e $(arg physics) $(arg extra_gazebo_args) $(arg world_name)" />

  <group if="$(arg gui)">
    <node name="gazebo_gui" pkg="gazebo_ros" type="gzclient" respawn="false" output="screen"/>
  </group>

  <param name="robot_description" command="$(find xacro)/xacro '$(find simple_camera_model)/simple_camera_model.xacro'" />


  <node name="spawn_urdf ...